Damage Calculator
Real-time combat math — results update as you type
Enemy
Your Attack
Your Defense
Damage = floor((0 + 0) × 1.0 × 1.0) × 1 − 0 block = 0
How to Use the Slay the Spire 2 Damage Calculator
The Damage Calculator eliminates guesswork from combat decisions. Enter your stats and the enemy stats — results update instantly at the top of the page so you never have to scroll to see if your attack is lethal.
This is most useful when you're unsure whether to spend energy on offense or defense. If the calculator confirms lethal, skip block cards. If not, prioritize surviving the incoming hit.
Understanding the Damage Formula
- •Vulnerable multiplies damage taken by 1.5. Apply it to the enemy before attacking for maximum value.
- •Weak reduces outgoing damage by 25% (×0.75). Factor this in when debuffed.
- •Frail reduces block gained by 25% (×0.75). You need more block cards to compensate.
- •Multi-hit attacks apply modifiers per-hit but subtract enemy block only once from the total.
When to Attack vs Block
Prioritize Attacking When:
- • The calculator confirms lethal this turn
- • The enemy has Strength scaling up next turn
- • You have active Strength buffs to maximize
- • The enemy is about to gain Block or Regenerate
Prioritize Blocking When:
- • The enemy's next move is a heavy attack
- • You're at low HP with no healing available
- • You have Barricade and block carries over
- • The enemy will take multiple turns to kill anyway
Common Status Effect Reference
Tip: Use the Attack Pattern Viewer alongside this calculator — look up the enemy's incoming damage, then calculate if your block covers it.
Frequently Asked Questions
Does Vulnerable apply before or after Strength?
Strength is added to base damage first, then Vulnerable multiplies the result. So a 6-damage attack with 2 Strength and Vulnerable deals floor((6+2)×1.5) = 12 damage.
Do multi-hit attacks pierce block multiple times?
No. In Slay the Spire 2, enemy block is subtracted from the total combined damage of all hits, not per-hit. However, each hit does apply modifiers like Vulnerable separately.
Does Weak affect the enemy or me?
Weak reduces the damage dealt by the Weakened entity. If the enemy is Weak, they deal 25% less damage to you. If you are Weak, you deal 25% less damage to them.
What is Dexterity and how does it interact with Frail?
Dexterity adds flat block to every block card you play. Frail then reduces the total block gained (including Dexterity bonus) by 25%. The calculator handles this automatically.
Can I use this calculator for X-cost cards?
Yes. For X-cost attacks like Whirlwind, enter the damage per hit and the number of hits based on your current energy. The calculator will multiply correctly.