Whirlwind costs X Energy and hits all enemies 5 times × X (8× upgraded). The whole build exists to make X as large as possible. Offering and Bloodletting burst-generate Energy; Energy relics add to each turn's pool; Strength multiplies every single hit. On a 6-Energy turn against 3 enemies, upgraded Whirlwind deals 48 damage to each — without any Strength. Add 15 Strength and every hit becomes 23 damage, totaling 138 AoE per turn. Nothing in the game handles large groups faster.

• Whirlwind: Attack costing X. Deal 5 damage to all enemies X times (8× upgraded). The payoff card — build everything to inflate X.
• Offering: Skill costing 0, Exhaust. Lose 6 HP, gain 2 Energy and draw 3 cards. A free +2 Energy for the same turn as Whirlwind; can push X from 3 to 5 single-handedly.
• Bloodletting: Skill costing 0. Lose 3 HP, gain 2 Energy (3 upgraded). Lighter than Offering; stack multiple copies for reliable Energy surges each turn.
• Demon Form: Power costing 3. Gain 2 Strength per turn. Every Strength point adds 5×X damage to each Whirlwind hit — even 5 Strength is a substantial multiplier.
• Inflame: Power costing 1. Gain 2 Strength immediately. Cheaper than Demon Form and front-loads Strength before your first Whirlwind.
• Feel No Pain: Power costing 1. Gain 3 Block whenever you Exhaust. Offering triggers Feel No Pain for free Block, keeping HP sustainable.

• Crismon Cloak / Energy Relics: Any relic that adds 1 or more Energy per turn directly raises X on every Whirlwind by 1, adding 5+ hits total. These are highest priority in shops.
• Akabeko: First attack each combat deals 8 extra damage. On a multi-hit Whirlwind first-attack, this adds 8 per hit — massive burst on the opener.
• Runic Pyramid: Retain hand at end of turn. Lets you hold Offering and Bloodletting for the exact turn you want to detonate, rather than cycling them away.

1. Collect Energy relics and Energy-generating cards first — Whirlwind needs at least X=4 to be worthwhile, so aim for reliable 5+ Energy turns.
2. Each turn before Whirlwind: play Offering and Bloodletting first to maximize X, not after.
3. Stack Strength via Demon Form and Inflame for the full multiplier effect; even 8-10 Strength makes each hit substantially stronger.
4. In single-enemy fights, Whirlwind is less efficient than direct-damage cards — use it for multi-enemy rooms where the AoE advantage is decisive.
5. Against Vulnerable enemies, the damage multiplier compounds with Strength; apply Vulnerable (via Upper Cut) before Whirlwind for 50% extra.

• Whirlwind: Absolute must — only pick if Strength and Energy scaling are viable.
• Offering / Bloodletting: Must take both — they are the Energy burst that makes large X possible.
• Demon Form: High — Strength multiplied across many Whirlwind hits adds up faster than in single-target builds.
• Energy relics (shop): Highest — each +1 Energy relic is a permanent +5-8 damage per Whirlwind hit.
• Inflame: High — cheap Strength front-load before the main engine is running.
• Feel No Pain: Medium — if running Offering it makes the HP trade more sustainable.

• Order of play in a single turn: Offering → Bloodletting → (optional block cards) → Whirlwind. Never play Whirlwind before Energy generators.
• Upgraded Bloodletting gives 3 Energy at 0 cost — prioritize its upgrade over most other cards.
• Whirlwind at X=0 deals 0 damage. If you have no Energy left, don't play it — hold it for next turn.
• In Act 3, elite fights often have 2 enemies. Opening with Offering → Bloodletting → Whirlwind at X=5 deals 40 damage to each enemy (plus Strength) before anyone acts.
• Runic Pyramid's hand-retention lets you save Offering for turns where you need maximum Energy, rather than being forced to play it when drawn. This is a significant upgrade to the build's consistency.