“One of list is Dooms’ symphony.”
Overview
Isaac
Symphonic Warrior
Watchers
Advanced Elite
Single Damage
AOE Damage
4: Standard carry slot. Fires after supports have applied shields and debuffers have softened targets. Back-row position keeps Isaac safe while Overture’s fight-back activates from any row.
3: Earlier firing position. Isaac can apply Variation before other carries act, setting up +50% WPN DMG debuff for teammates. Slightly more exposed than pos 4.
5: Safest back-row slot when another carry needs pos 4. Still receives full Overture counter-attack benefits. Slightly later in Super Core cycle.
Isaac is a counter-attacking commando who punishes enemy focus skills with Overture’s team-wide fight-back and applies Variation to lock targets into escalating damage and Silence. His La Danse Macabre focus skill delivers 300% WPN DMG to a single enemy while granting +50% Initiative for 2 rounds, and Grand Finale triggers 200% WPN DMG to all enemies on kill plus auto-Silence on his next focus skill. Last Show UW applies Variation to 3 enemies at battle start, doubles focus skill WPN DMG, and stacks up to +100% DEF ignore from teammate actions, making Isaac a devastating reactive carry who grows stronger as the fight progresses.
Pros & Cons
- Overture triggers a team-wide fight-back against ALL enemies (50% WPN DMG + 30% Silence chance) whenever Isaac is hit by an enemy focus skill, punishing skill-reliant lineups.
- Swaying Variation applies +50% WPN DMG taken (once) and Silence after 3 hits on the target, combining damage amplification with crowd control on a single debuff.
- Grand Finale deals 200% WPN DMG to all enemies on kill and makes the next focus skill directly Silence the target, creating devastating snowball potential after the first kill.
- Last Show UW applies Variation to 3 enemies at battle start, doubles focus skill WPN DMG, and stacks up to +100% DEF ignore from teammate actions, scaling damage throughout the fight.
- Concerto exclusive gear 2-piece reduces first DMG taken each round by 50%, providing surprising durability for a back-row carry.
- Overture’s fight-back only triggers when Isaac is hit by an enemy focus skill (1x/round), providing zero value against lineups that avoid targeting him or rely on normal attacks.
- Silence-immune heroes completely negate Variation’s Silence component and Overture’s 30% Silence chance, removing a core part of Isaac’s kit.
- Focus drain from Casino’s Double Down delays La Danse Macabre, preventing Isaac from applying Variation and reaching Grand Finale’s kill threshold.
- No self-sustain or shielding; relies entirely on teammates for survival between his reactive counter-attack turns.
Skills
Deals 180/204/228/252/300% WPN DMG to 1 enemy target. The hero’s Initiative increases by 25/30/35/40/50% for 2 rounds.
When Isaac is hit by a Focus skill, he will fight back against all enemy targets, dealing 25/30/35/40/50% WPN DMG, with a 15/18/21/24/30% chance to Silence them for 1 round (the chance for each target will be calculated separately). The effect can be triggered once only each round.
When Isaac casts a Focus skill, he applies a Variation effect to the target. The target subject to the Variation effect will take 25/30/35/40/50% additional WPN DMG once and be Silenced after taking DMG 7/6/5/4/3 times, lasting 1 round.
Deals 60/68/76/84/100% additional WPN DMG when casting "La Danse Macabre".
When Isaac kills an enemy, deals 120/136/152/168/200% WPN DMG to every enemy target individually; the next time "La Danse Macabre" is cast, the target will be Silenced directly.
Gear
Concerto is best-in-slot — the 50% damage reduction per round and enhanced fight-back define Isaac’s reactive carry identity. Resolute is mandatory for survivability. Reaper is the strongest offensive alternative, directly synergising with Isaac’s Variation debuff on wounded targets. Pair Concerto + Resolute as the standard setup.
Exclusive set. 2-piece reduces first DMG taken each round by 50%, providing significant durability. 4-piece makes fight-back deal +50% DMG and applies Variation to 1 additional enemy, expanding Isaac’s reactive reach.
#1 Best
Standard DPS survivability set. +0.4% ATK per 1% HP lost. 4-piece death immunity with 30% HP restore and +50% DMG on the next attack. Essential safety net for a 299 VIT hero.
#2
+15% Crit Rate and +30% Crit Damage. Isaac’s focus skill hits for 300% WPN DMG (doubled by Last Show UW) — critting on this massive hit is devastating. Strong with Buri’s Frosty Coffin.
#3
+10% ATK and +35% DMG after defeating target. Isaac’s Grand Finale triggers on kill with 200% WPN DMG AOE — Death’s post-kill bonus compounds with the next focus skill’s auto-Silence.
#4
Normal attacks cause bleeding for sustained damage between skill casts. Budget option for early investment. Bleeding procs can trigger Blaze Shark in Heytex lineups.
#5
+10% DMG Bonus and +25% DMG to targets below 50% HP. Isaac’s Variation debuff (+50% WPN DMG taken) combined with Reaper’s below-50% bonus creates devastating damage on wounded targets.
#6
Isaac is a STR-based carry dealing WPN DMG. Prioritize STR and damage stats on weapon and jewelry (offensive slots), and HP/DEF/VIT on helmet and body (defensive slots). Do not roll INT or TAC ATK substats — Isaac has no TAC DMG skills.
DMG Bonus, STR, Crit Rate
DMG Bonus is a universal multiplier. STR scales WPN ATK for all of Isaac’s damage skills including La Danse Macabre, Overture fight-back, and Grand Finale AOE.
HP%, AGI, VIT
Survivability stats. HP% is the most efficient. AGI reduces incoming damage and helps Isaac survive long enough for Overture fight-backs and Variation stacks to accumulate.
DEF, VIT, DMG Mitigation
Pure defense. Isaac’s 299 VIT makes him fragile; Concerto’s 50% first-hit reduction stacks with high DEF for meaningful round-over-round survivability.
DMG Bonus, STR, Skill Effect Enhancement
DMG Bonus multiplies everything. STR scales WPN ATK. Skill Effect Enhancement boosts La Danse Macabre and Grand Finale multipliers.
Recommended lineups
Archetype tags describe playstyle. Each card shows recommended gear (helmet icons), APC parts, and War Beast. Open APC · View details for part skills and calculator link.
Beast 
Triple-carry lineup with Isaac, Kelly, and Victoria. Crimson Predator’s ATK, DMG Bonus, and Crit Rate maximise damage output across all three damage dealers.
Primary tank. Scarlet Authority UW grants +10% DMG and +10% healing/shield. Duke exclusive gear adds +4% DMG to all Watchers. Super Core accelerates focus from pos 1.
Staunch Will shields all allies, feeding Victoria’s Energy Detection. Chimera Anchor UW deals chip damage per shield event. Alpha Bless provides round 1 shields and crit immunity.
Primary carry. Last Show UW applies Variation to 3 enemies at battle start and doubles focus skill WPN DMG. Overture fights back against all enemies when hit by focus skills. Concerto’s 50% damage reduction keeps him alive for extended fights.
Independent assassin. Targets lowest-AGI enemy. Spine Whip UW gives 50-100% chance for a second action each round. Cat Soul shreds target DMG Mitigation. Isaac’s Variation Silence prevents the target from using focus skills, complementing Kelly’s burst.
Shield-scaling carry. Energy Detection copies shields from Harman and Alpha Bless. Lightsword adds 250% of shield as burst damage. Thunder Blade UW grants +200 Focus, +15% DMG in back row.
Isaac and Victoria as dual carries in a Watchers core. Roland tanks and provides Scarlet Authority’s +10% DMG. Harman layers shields feeding Victoria’s Energy Detection while Isaac applies Variation to priority targets. Kelly adds independent single-target assassination. Isaac’s Variation Silence shuts down enemy carries while Victoria’s Lightsword bursts down debuffed targets. Full 5 Watchers for +20% ATK/HP faction bonus.
Beast
Triple-carry lineup with Isaac, Macklin, and Victoria. Crimson Predator’s offensive stats maximise damage output across all three.
Primary tank. AC Shield UW provides 200% max HP shield at battle start. Super Core accelerates focus from pos 1. Alpha Bless provides team-wide round 1 shields and crit immunity.
Staunch Will shields all allies, feeding Victoria’s Energy Detection. Chimera Anchor UW deals chip damage per shield event. Guardian INT scales shield size with rounds elapsed.
Co-carry. Bounty marks provide team-wide buffs including Red (+15% DMG) that amplifies Isaac’s fight-back and focus skill hits. Executioner kills restore 500 Focus for chain-kills on Isaac’s Variation-debuffed targets.
Co-carry. Variation debuffs targets with +50% WPN DMG taken, setting up Macklin’s Executioner for easier kills. Reaper’s +25% DMG to targets below 50% HP compounds with Variation’s damage amplification. Grand Finale’s kill-triggered AOE cleans up weakened enemies.
Shield-scaling carry. Energy Detection copies shields from Bolton’s AC Shield, Harman, and Alpha Bless. Lightsword adds 250% of shield as burst damage. Dual carry support from Isaac’s Silence preventing enemy retaliation.
Isaac and Macklin as dual carries with complementary mechanics. Isaac’s Variation applies Silence and +50% WPN DMG taken, softening targets for Macklin’s Executioner kills. Macklin’s bounty marks provide team-wide buffs that amplify Isaac’s fight-back and focus skill damage. Bolton provides front-line tanking with AC Shield. Harman layers shields for survival. Victoria delivers shield-based burst as the third carry.
Beast
Dual-carry lineup with Isaac and Victoria. Crimson Predator’s offensive stats maximise damage output. Buri’s damage distribution handles survivability.
Primary tank. Link of Life distributes 50% of incoming damage with +24% DMG Mitigation. Frosty Coffin grants +15% crit rate and +30% crit DMG. Extended fights give Isaac more rounds for Variation stacks and Overture fight-backs.
Staunch Will shields all allies, feeding Victoria’s Energy Detection. Super Core accelerates focus bars from pos 2. Alpha Bless provides team-wide round 1 shields and crit immunity. Chimera Anchor UW deals chip damage per shield event.
Primary carry. Buri’s damage distribution extends fights, giving Isaac more rounds to apply Variation, trigger Overture fight-backs, and reach Grand Finale’s kill threshold. Frosty Coffin crit bonuses amplify his WPN DMG output.
Debuffer. Skeleton exclusive gear reduces enemy DEF and applies debuffs that soften targets for Isaac’s Variation (+50% WPN DMG taken). Layered debuffs from both Elaine and Isaac create multiplicative damage amplification for the entire lineup.
Shield-scaling carry. Buri’s damage distribution protects her from being sniped. Harman’s shields feed Energy Detection and Combat Master stacks. Frosty Coffin crit bonuses turn her Lightsword hits into frequent crits.
Buri’s Link of Life distributes 50% of incoming damage across all heroes, extending fights for Isaac’s Variation stacks and Overture fight-backs to accumulate value. Frosty Coffin UW grants +15% crit rate and +30% crit DMG while Link of Life is active, amplifying Isaac’s WPN DMG output. Elaine’s debuffs soften targets for Variation’s +50% WPN DMG taken, creating layered damage amplification. Victoria handles shield-based burst. Harman layers shields for Victoria and provides sustained healing.
Synergies
Isaac and Victoria cover complementary roles — Isaac locks down enemy carries with Variation Silence while Victoria delivers shield-scaled burst. Isaac’s Overture fight-back hits all enemies, softening multiple targets while Victoria eliminates the priority one. Dual carry coverage ensures pressure on multiple fronts simultaneously.
Isaac’s Variation Silences the target after 3 hits, preventing focus skills. Kelly’s Spine Whip double-action accelerates the hit count toward Silence threshold. Cat Soul’s DMG Mitigation shred compounds with Variation’s +50% WPN DMG taken for massive effective damage amplification on a single target.
Harman’s Staunch Will shields all allies every cast, providing survivability for Isaac’s 299 VIT frame. Chimera Anchor UW deals chip damage per shield event, adding sustained pressure alongside Isaac’s reactive fight-back damage.
Roland’s Scarlet Authority UW grants +10% DMG and +10% healing/shield to the entire lineup. Duke exclusive gear adds +4% DMG to all Watchers. Both buffs amplify Isaac’s La Danse Macabre and Grand Finale damage output while keeping him alive through enhanced shields.
Elaine’s Skeleton debuffs reduce enemy DEF and apply status effects that soften targets for Isaac’s Variation (+50% WPN DMG taken). Layered debuffs from both heroes create multiplicative damage amplification, making even tanky targets vulnerable to Isaac’s WPN DMG output.
Interactions with other heroes’ ultimate weapons.
Isaac’s Variation Silences enemy carries, preventing them from using focus skills while Victoria charges Lightsword. Thunder Blade’s +200 Focus at battle start lets Victoria fire early while Isaac’s Variation debuffs are still active on multiple targets. Dual carry coverage ensures the enemy faces both Silence and burst damage simultaneously.
Every time a teammate gains a shield, Chimera Anchor deals 50% TAC ATK to a random enemy. Isaac’s Concerto 2-piece 50% damage reduction and Overture fight-back keep him active through sustained fights, during which Harman’s shield events generate consistent Chimera Anchor chip damage alongside Isaac’s reactive counter-attacks.
Kelly’s Spine Whip grants 50-100% chance for a second action each round. More actions per round means faster Variation stack accumulation on shared targets — Kelly’s double-action can push a target to the 3-hit Silence threshold in a single round, enabling Isaac’s follow-up focus skill to hit a Silenced, debuffed enemy.
Ultimate weapons
Unlocked
At the start of the battle, applies the [Variation] effect to 1 enemy targets, making the Focus Skill additionally deal 50% WPN DMG.
★
At the start of the battle, applies the [Variation] effect to 2 enemy targets, making the Focus Skill additionally deal 60% WPN DMG.
★★
At the start of the battle, applies the [Variation] effect to 2 enemy targets, making the Focus Skill additionally deal 70% WPN DMG. Every time a teammate takes action, the hero applies a layer of [Concerto] effect to himself, each layer making his attack ignore 2% of the target’s DEF, stackable for up to 10 layers
★★★
At the start of the battle, applies the [Variation] effect to 3 enemy targets, making the Focus Skill additionally deal 80% WPN DMG. Every time a teammate takes action, the hero applies a layer of [Concerto] effect to himself, each layer making his attack ignore 3% of the target’s DEF, stackable for up to 15 layers
★★★★
At the start of the battle, applies the [Variation] effect to 3 enemy targets, making the Focus Skill additionally deal 90% WPN DMG. Every time a teammate takes action, the hero applies a layer of [Concerto] effect to himself, each layer making his attack ignore 3% of the target’s DEF, stackable for up to 20 layers
★★★★★
At the start of the battle, applies the [Variation] effect to 3 enemy targets, making the Focus Skill additionally deal 100% WPN DMG. Every time a teammate takes action, the hero applies a layer of [Concerto] effect to himself, each layer making his attack ignore 4% of the target’s DEF, stackable for up to 25 layers
Counters
- Silence-immune heroes (Hard Counter) — Variation’s Silence after 3 hits and Overture’s 30% Silence chance are core to Isaac’s kit. Heroes with Silence immunity completely negate these mechanics, removing Isaac’s crowd control contribution and reducing him to a pure damage dealer without unique value.
- Casino (Hard Counter) — Casino’s Double Down drains 200 Focus from all enemies on skill cast. Isaac’s La Danse Macabre needs Focus to apply Variation and reach Grand Finale’s kill threshold. Focus drain delays his critical first cast and prevents the kill-triggered snowball.
- Focus skill-reliant heroes (Hard Counter) — Isaac’s Overture triggers a team-wide fight-back (50% WPN DMG + 30% Silence) whenever Isaac is hit by an enemy focus skill. Heroes who depend on focus skills for their value (Victoria, Kelly, Heytex) trigger Overture and risk being Silenced, shutting down their primary damage.
- Single-target snipers (Soft Counter) — Overture’s fight-back hits ALL enemies when Isaac is hit by any focus skill. Single-target snipers who focus Isaac trigger team-wide retaliation, turning their precision into a disadvantage as the entire enemy lineup takes 50% WPN DMG.
Rating
A Tier. Isaac is an A-tier carry from Season X4 onward. His Variation mechanic provides a unique damage amplification and Silence combo that no other hero replicates — targets take +50% WPN DMG once and are Silenced after 3 hits. Overture’s team-wide fight-back when hit by an enemy focus skill adds AOE pressure that punishes skill-reliant lineups. However, Isaac’s value depends on enemies using focus skills to trigger Overture, making him situational against lineups that rely on normal attacks or DOT damage.
Videos
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Skins
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Trivia
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