Senna: The Redeemer

Senna is a Bottom/Support champion released on November 10, 2019. Classified as Marksman and Enchanter (legacy: Support, Marksman), she plays both roles depending on composition. She is Ranged with 600 base attack range (scaling with Mist stacks), adaptive type Physical, using Mana. Missile speed: Non-projectile (beam-based attacks). Base MS: 330.

Last changed patch V26.04. Store price: 1575 BE / 790 RP. Senna is the only champion in the game whose base AD is fixed at 50 and does not scale per level. All AD growth comes exclusively from Mist stacks through Absolution. This makes her unique: a champion who is intentionally weak in standard last-hitting patterns and scales entirely through passive stack collection. Her crit damage is penalized (180% + 27% instead of standard 200%), but excess crit above 100% converts to life steal – creating a natural sustain synergy with crit builds.

📊 Base Statistics

💡 Key Note – Fixed AD and AS Ratio: Senna’s AD is fixed at 50 with zero level scaling. Every point of bonus AD comes from Mist stacks (0.75 AD per stack). At 200 Mist stacks: +150 bonus AD above base 50 = 200 total AD. Her attack speed ratio is 0.4 – she gains only 0.4 attack speed per 100% bonus attack speed from items. This intentionally makes AS items inefficient on Senna. Her windup is also reduced only by 60% of the expected value from AS bonuses. Attack speed is not a meaningful stat on Senna – bonus AD and crit are her scaling stats.

Passive: Absolution – The Mist System

Weakened Soul – Mark System

INNATE: Senna’s basic attacks, on-hit effects, and abilities mark enemy champions hit for 4 seconds. Subsequent attacks or ability hits against marked targets consume the mark to grant Senna a stack of Mist and deal bonus physical damage equal to 1%–10% (based on level) of the target’s current health. Rendering the target immune to being marked again for a few seconds. This damage applies life steal at 100% effectiveness.

Mist Wraith – Soul Collection

INNATE: Enemies that die near Senna may spawn a Mist Wraith from their corpse. A Mist Wraith lasts 8 seconds. Senna can basic attack or hit it with Piercing Darkness or Dawning Shadow to kill it instantly, granting 8 gold and a stack of Mist.

💡 Why Senna Should NOT Last-Hit Minions: Minions that Senna kills have only a 10% Mist Wraith spawn chance. Large minions that Senna does not kill always spawn a Mist Wraith. Lesser minions Senna does not kill have a 28% spawn chance vs. 10% if she kills them. Letting ally or the ADC last-hit minions generates approximately 3× more Mist Wraiths per minion than Senna killing them herself. This is counter-intuitive for every standard ADC and support habit, but the passive explicitly rewards non-last-hitting. The Support Q’s 8.4% chance on executed minions adds a small additional stream when playing Support role.

Mist – Scaling Stats

MIST SCALING:

• +0.75 bonus attack damage per stack of Mist
• +20 bonus attack range per 20 stacks of Mist
• +10% critical strike chance per 20 stacks of Mist
• Every 1% critical strike chance in excess of 100% converts to 0.35% life steal

💡 Late Game Mist Value: At 200 Mist stacks (achievable in long games with consistent Wraith collection), Senna has 200 total AD, 800 attack range, and 100% crit chance from passive alone, before any items. Item AD, AP, and crit then add on top of this baseline. Senna’s late-game power scales with game duration and Mist collection rate more than any other ADC. A well-collected 35-minute Senna significantly outranges and outdamages a 20-minute Senna.

Relic Cannon – Basic Attack Empowerment

INNATE: Senna’s basic attacks on-hit deal 20% AD bonus physical damage and grant her 10% / 15% / 20% (based on level) of the target’s movement speed as bonus movement speed for 0.5 seconds. The damage applies life steal at 100% effectiveness.

Q: Piercing Darkness

Cost: 70/80/90/100/110 Mana  |  CD: 15 sec (reduced by 1s per on-hit)  |  Cast Time: 80% of Senna’s windup time (0.4 at base AS)  |  Target Range: 600–1100  |  Range: 1300  |  Width: 100/280

ACTIVE: Senna fires a beam in the direction of the target unit. The beam consists of a wider ray of light and a narrower ray of shadow at the center.

SHADOW RAY: Deals physical damage to enemies hit and slows them by 15% (+15% per 100 bonus AD)(+10% per 100 AP) for 1/1.25/1.5/1.75/2 seconds. Applies life steal at 100% effectiveness.

LIGHT RAY: Heals Senna and allied champions hit.

💡 Pro Tip – Q Cooldown Reduction via On-Hit: Piercing Darkness reduces its own cooldown by 1 second per on-hit effect triggered. Items like Kraken Slayer, Phantom Hit, or on-hit effects all trigger this reduction. In an active fight with multiple on-hit procs, Q’s effective cooldown can drop well below its base 15 seconds. Additionally, the cast time scales with Senna’s windup reduction – faster windup via levels (31.25% → 21.875%) means faster Q casts over time.

⚠️ Targeting Requirement: Piercing Darkness must be targeted on a unit – a champion, minion, turret, or ward. It cannot be cast freely in a direction without a target. In lane, use the closest ally minion as a targeting anchor to fire Q through the enemy champion. This is Senna’s primary poke and heal delivery mechanism simultaneously.

W: Last Embrace

Cost: 50/55/60/65/70 Mana  |  CD: 11 sec  |  Cast Time: 0.25  |  Target Range: 1300  |  Effect Radius: 280  |  Width: 140  |  Speed: 1200

ACTIVE: Senna throws a globule of Black Mist in the target direction that deals physical damage to the first enemy hit and attaches to them for 1 second. After the duration or when the target dies, the Black Mist spreads out from the target, rooting them and surrounding enemies for a duration.

💡 Pro Tip – Death Detonation: If the attached target dies during the 1-second attachment window, the Black Mist spreads immediately rather than waiting for the full second. In teamfights where an enemy dies to combined damage while W is attached, the root detonates instantly on surrounding enemies. This creates scenarios where killing the W target as quickly as possible triggers a surprise root on the enemies standing near them – a common setup in coordinated 2v2 trades.

⚠️ W Is a Skillshot with 1-Second Delay: W attaches on hit but the root doesn’t apply for 1 full second. Opponents who Flash or use movement abilities during that second avoid the root entirely. Against Flash-up opponents, W is best used after their Flash is on cooldown or used offensively first so they’ve already burned it. The 1300 range also means W has a travel time that alert opponents can sidestep.

E: Curse of the Black Mist

Cost: 70 Mana  |  CD: 26/24.5/23/21.5/20 sec  |  Cast Time: 1 sec  |  Effect Radius: 400  |  Detection Radius: 400

ACTIVE: Senna shrouds herself in an aura of Black Mist and gains camouflage for a duration. If Senna breaks the camouflage, she regains it after 1.75 seconds without performing actions that break stealth. Senna can move during Curse of the Black Mist’s cast time.

WRAITH FORM: Allied champions who enter the mist gain Wraith Form for a duration equal to the aura’s remaining duration. Wraith Form grants camouflage. Enemies are granted obscured vision of camouflaged Wraiths moving outside the mist within their line of sight. Wraith Form can be regained if lost by returning to the mist within 1.75 seconds. Wraith Form ends immediately upon Senna’s death.

💡 Pro Tip – E as Team Engage Tool: Curse of the Black Mist camouflages Senna and all allies within the 400-radius moving aura. This means Senna walking the mist cloud toward a fight brings the entire nearby team invisible with her. In lane, walking E toward a bush with the support creates a camouflaged 2v2 approach. In teamfights, mid-fight activation with the team clustered inside camouflages the entire team during a brief retreat or repositioning window. The 20% movement speed bonus during E means the repositioning is faster than normal movement while invisible.

⚠️ Obscured Vision Limitation: Enemies are granted obscured vision of Wraith Form allies moving outside the mist within their own line of sight. This means the camouflage is not full invisibility like Twitch or Evelynn – enemies near the exiting Wraith can roughly see their location when they move outside the mist cloud. The protection is strongest within the mist radius and while the team stays inside Senna’s moving aura.

R: Dawning Shadow (Ultimate)

Cost: 100 Mana  |  CD: 140/120/100 sec  |  Cast Time: 1 sec  |  Target Range: GLOBAL  |  Width: 320/2400  |  Speed: 20000

ACTIVE: Senna fires a massive beam in the target direction. The beam consists of a broad wave of light and a narrow wave of shadow at the center.

SHADOW WAVE: Deals physical damage to enemy champions hit and reveals them for 3 seconds. Also hits all Mist Wraiths in the path.

LIGHT WAVE: Grants a shield to Senna and allied champions hit for 3 seconds and grants sight of the area along the path for 2 seconds.

💡 The Shield Scales with Mist Stacks: Dawning Shadow’s light wave shield strength is 120/160/200 (+50% AP)(+1.5 per Mist stack). At 200 Mist stacks and rank 3 R: 200 + 300 Mist bonus = 500 HP shield base before AP adds further. With 300 AP from items: 500 + 150 = 650 HP shield applied to every ally hit by the global light wave. In a 5v5 teamfight where R shields all 5 allies, this is effectively 3250 HP of total shielding distributed across the team from a single button press. Mist stack collection directly increases the team’s survivability on every R cast.

💡 Pro Tip – Global Engagement: Dawning Shadow’s global range at 20000 speed means it reaches across the entire map near-instantly. It can shield allies in a distant fight while Senna is in a completely different location. Coordinate with the team: when allies start a fight in another lane or jungle, a global R shields them before the fight even fully develops. Also collect all Mist Wraiths in the beam’s path, accelerating passive stack accumulation during the cast.

⚠️ Shadow Wave Width is Narrow: The damage component (shadow wave) is only 320 units wide – much narrower than the 2400-wide light wave. Hitting specific enemies requires aim. The light wave at 2400 width is extremely forgiving and hits nearly all allies on the same side of the map. In teamfights, prioritize aiming the shadow for the damage priority target (enemy carry) rather than trying to hit multiple enemies with the narrow center.

🎯 Strategies and Gameplay Tips

Early Game (Levels 1–6)

• Never Last-Hit Minions as ADC Senna: In the ADC role, the instinct to last-hit is the primary habit to override. Large minions you don’t kill always spawn Mist Wraiths. Lesser minions you don’t kill have 28% spawn chance. Prioritize poking the enemy with Q and letting the support or ally kills generate the wraiths. The gold loss from non-last-hitting is compensated by Mist stack AD scaling and the 8 gold per collected Mist Wraith.
• Q Through Ally Minions for Poke: Piercing Darkness must be targeted on a unit. Use the frontline minion nearest the enemy as a targeting anchor – Q fires through the minion and hits the enemy champion behind it with the shadow ray, dealing damage and applying slow, while the light ray heals Senna and any ally standing between the two. This simultaneous poke + heal pattern is the lane phase identity.
• W for Lane Engagement with CC Support: Against CC-support pairings (Nautilus, Thresh), the W attachment + 1-second delay root perfectly follows the CC chain. Support hooks → Senna W attaches → combined damage during 1-second window → target dies → Black Mist immediately spreads to surrounding enemies → root on the support standing next to the original target.

Mid Game (Levels 7–13)

• E for Safe Rotation: Curse of the Black Mist at rank 3 (7-second duration) with the team clustered nearby creates a team-wide camouflage rotation across the map. Walking from mid to bot lane covered by E allows the entire team to arrive undetected. The 20% MS bonus means the rotation covers ground faster than a standard walk. Use E before entering the enemy’s ward line, not after being spotted.
• Global R Timing in Teamfights: Track the minimap for fights happening elsewhere. When allies engage with HP below 50%, a global Dawning Shadow light wave shields them before burst damage completes. The near-instant speed (20000) means R fired the moment a fight starts at 1000 units away arrives within 0.05 seconds. Reaction-time use of global R saves more lives than carefully aimed R damage in most mid-game scenarios.
• Mist Wraith Collection Priority: Epic monster deaths (Baron, Dragon) spawn 2 Mist Wraiths. Always be in position to collect both after an objective kill. Enemy champion deaths always spawn a Mist Wraith – position near dying enemies to collect the soul before it expires at 8 seconds. A missed Mist Wraith is 0.75 lost bonus AD and a lost attack range step every 20 stacks.

Late Game (Level 14+)

• Mist Stack Threshold Tracking: Know your current Mist stack count and the thresholds. At 180 stacks: 90% crit from passive. Items bringing you to 100%+ crit converts excess to 0.35% life steal. At 200+ stacks, every additional 20 stacks adds 20 attack range and 7% more life steal from excess crit. Late game Senna with 200+ stacks is outranging almost every ADC while sustaining through life steal on every basic attack.
• Dawning Shadow as Team Shield Wall: At rank 3 with 200 Mist stacks and 300 AP, each R light wave shield is approximately 650 HP per ally. In a 5v5 where all allies are hit, total shielding exceeds 3000 HP distributed. Use R at the start of a teamfight when allies are full HP – the 3-second shield duration covers the initial burst phase before tank items can absorb the damage flow.
• Q Slow Scaling with Bonus AD: Q’s slow scales at +15% per 100 bonus AD above the 15% base. At 200 Mist stacks (150 bonus AD) plus 100 bonus AD from items: +45% additional slow = 60% total slow from a single Piercing Darkness hit. A 60% slowed target combined with Last Embrace’s root means the target effectively stops moving for the 2.25-second max rank root duration after being slowed first.

⚔️ Core Combo Guide

1. Standard Lane Poke + Heal: Target nearest ally minion → Q (shadow damages enemy, light heals ally + Senna) → Weakened Soul mark auto on enemy → mark consumes for Mist stack + current health damage → W if root window available after mark proc
2. All-In with CC Support: Support CC → Senna W attaches to CC’d target (1 second) → full auto combo + mark proc on target during W attachment → target dies → W Black Mist spreads → root on surrounding enemies → global R light wave shields team
3. E Rotation Engage: Team clusters near Senna → E activates (team camouflages, +20% MS) → walk toward objective or enemy position while invisible → enter fight range → Q auto combo → W for root → R for shield and damage
4. Global R Defensive Save: Ally fight detected on minimap → R aimed at ally cluster (light wave priority) → shields arrive near-instantly → shadow wave damages any enemies in path → collect Mist Wraiths hit by R shadow

❌ Common Mistakes and How to Avoid Them

• Last-Hitting Minions as Senna ADC: The single most damaging habit for Senna’s scaling. Minions Senna kills: 10% Wraith spawn chance. Minions Senna doesn’t kill: 28% chance (lesser) or 100% (large). Actively avoid last-hitting and let the support or ally last-hit. The gold difference is small; the Mist stack difference over 30 minutes is enormous.
• Q Without a Unit Target Available: Attempting to Q in a direction without a targetable unit in the cast direction results in no cast. Against enemies hiding behind their minion wave with no allied minion nearby to target through, Q has no angle. Manage minion wave positioning to always maintain a targetable unit in the direction of the enemy carry.
• W Into Flash-Ready Opponents: W’s 1-second attachment window is a Flash opportunity. Use W only after enemy Flash is on cooldown, has been used defensively, or when the enemy is already immobilized by another CC source. W into a 100% Flash-ready enemy in a 1v1 scenario results in a wasted 11-second cooldown.
• E After Being Spotted: Curse of the Black Mist grants camouflage, not true invisibility. Activating E after the enemy has vision of Senna’s position provides limited value – the enemy already knows the location and the obscured vision still shows movement. Activate E before entering the enemy’s ward line or before the enemy can see Senna’s approach.
• Aiming R for Shadow Damage Over Light Shield: The shadow wave (320 width, damage) requires precise aim. The light wave (2400 width, shield) is nearly impossible to miss with allies. When allies need the shield urgently, prioritize the light wave direction over shadow wave damage. Killing an enemy with R shadow is far less impactful than shielding 5 allies before their death from burst.

⚙️ Recommended Build and Itemization

ADC Build (Bottom Lane)

• Kraken Slayer: True damage on every third attack applies on-hit, which reduces Piercing Darkness cooldown by 1 second. Against tanky compositions, Kraken’s true damage bypasses armor on a champion whose primary scaling is AD but who has lower base attack speed. Each Kraken proc is also a Q cooldown reduction trigger.
• Infinity Edge: Senna’s passive generates crit stacks naturally (+10% per 20 Mist). IE’s crit amplification converts each auto into higher damage. At 100% crit from passive (200 Mist stacks), every auto and Q hit crits. Excess crit above 100% then converts at 0.35% life steal per 1%, creating sustained healing through crit.
• Rapid Firecannon / Runaan’s Hurricane: RFC provides range extension, amplifying Senna’s already-increasing range from Mist stacks. Runaan’s provides attack speed (partially reduced by 0.4 ratio) and multi-target bolts that each trigger Weakened Soul marks – accelerating Mist stack generation in teamfights against multiple targets.

Support Build

• Shurelya’s Battlesong: Active movement speed synergizes with E’s movement speed bonus, creating a brief window of extreme mobility during engage sequences. Healing and shielding power amplifies Q’s light ray healing and R’s shield strength.
• Redemption: Global healing zone complements Senna’s global R shielding pattern. Using Redemption + R simultaneously on a distant fight provides both a shield and delayed healing – stacking defensive value from a safe position.
• Moonstone Renewer: Healing per ability cast stacks with Q’s heal output. Senna’s frequent Q casts (reduced by on-hit) in fights generate consistent Moonstone heals to the lowest-HP ally simultaneously with Q’s own healing. Double heal per Q cast in teamfights.

⚔️ Counter Picks & Matchups

✅ Senna Counters

1. Soraka – No ability to prevent Senna’s Q poke at 600–800 range. Soraka’s Equinox (E) silence has a smaller effective zone than Senna’s Q range. Senna’s W root attachment forces Soraka out of healing position during the root window.

2. Janna – Janna’s peel and shield pattern cannot stop Senna’s global R impact. Monsoon (R) knockback interrupts Senna’s all-in but doesn’t prevent the global shield. Senna outranges Janna in all poke scenarios after Mist stack scaling begins.

3. Lulu – Lulu’s polymorph and shield are reactive to Senna’s poke pattern but cannot prevent the Q heal delivery or the global R shield. Last Embrace root on Lulu during the attachment window eliminates her peel capability for the root duration.

❌ Senna is Countered By

1. Draven – High early damage output during Senna’s weakest phase (pre-100 Mist stacks). Draven’s Spinning Axes deal more damage than Senna’s Q poke at equal levels. In the 10–15 minute window before Senna’s scaling overtakes, Draven can force significant HP trades that Senna cannot fully recover from through Q healing.

2. Caitlyn – 650 base attack range vs. Senna’s 600 creates an early lane range advantage before Mist stacks add range. Caitlyn’s Yordle Snap Trap (W) immobilizes Senna, preventing her from dodging Last Embrace’s 1-second attachment or positioning for Q angles. Headshot passive outpokes Q poke at low Mist counts.

3. Yasuo – Wind Wall blocks Senna’s Q shadow ray, Last Embrace globule, and Dawning Shadow shadow wave. Against Yasuo, all three of Senna’s primary ranged abilities are blockable by a single ability. Blade mode auto-attacks within 200 units bypass Wind Wall but require Senna to commit to melee range against a gap-close champion.

FAQ

Q: Should Senna always avoid last-hitting minions?

A: Yes, deliberately. Minions Senna kills have only a 10% Mist Wraith spawn chance. Large minions she doesn’t kill spawn a Mist Wraith 100% of the time. Lesser minions she doesn’t kill have a 28% chance. Letting ally last-hits generate Mist Wraiths produces approximately 2–3× more souls per minion than Senna killing them herself. This is intentional game design, not a bug.

Q: How does excess crit above 100% work?

A: Every 1% crit chance above the 100% cap converts to 0.35% life steal. Senna’s passive generates 10% crit per 20 Mist stacks. At 200 stacks: 100% crit from passive alone. Adding crit items or runes above 100% generates life steal at 0.35 per excess percent. At 120% crit from passive + items: 7% life steal from the 20% excess. This conversion makes high crit builds self-sustaining at late-game stack counts.

Q: Can Dawning Shadow shield specific allies?

A: No – the light wave travels in the aimed direction and hits all allies in the 2400-width path. The shield cannot be targeted to specific individuals. Position R in the direction of the largest ally cluster, or aim it to cross the maximum number of allies in a teamfight. The global range means R can be fired from anywhere on the map to reach allies in a different location.

Q: Does Q heal the caster (Senna) as well?

A: Yes. Piercing Darkness’s light ray heals Senna and allied champions hit. Senna always receives the heal as the caster. In a 1v1 without allies nearby, Q still heals Senna through the light component while damaging the enemy through the shadow component. This dual-function makes Q the primary sustain tool in lane, not just an ally-support ability.

Q: Is Senna better as ADC or Support?

A: Both are viable at high levels, but they serve different purposes. ADC Senna focuses on Mist stack accumulation for personal damage scaling. Support Senna pairs with a standard ADC carry and contributes healing, CC, and global R shielding while the ADC handles primary damage. In solo queue, ADC Senna provides more agency since the scaling is personal rather than dependent on the ADC carry performing.