Necro Mastery

Necro Mastery

Buff
Whenever Osty loses HP, ALL enemies lose that much HP as well.

Whenever your Osty's current HP goes down, every hittable enemy loses that same amount, multiplied by the stack count, as unblockable unpowered damage. Osty steps in front of unblocked powered attack damage aimed at you, so each enemy hit that Osty absorbs is mirrored back onto the whole enemy side. Necro Mastery also Summons 5 (8 upgraded) when played.

Kind
Necro MasteryBuff
Stacks
Yes
Character
Applied by
1 card

Where it comes from

Cards that apply Necro Mastery

Necro Mastery
Power
2
Summon 5.
Whenever Osty loses HP,
ALL enemies lose that much HP as well.
Summon 5.
Whenever Osty loses HP,
ALL enemies lose that much HP as well.

Notes

The mirrored number is what Osty actually lost, so an Osty on 3 HP taking a 12 damage hit costs the enemies 3. Summon raises Osty's Max HP or revives him, which is the fuel. Only Osty belonging to the power's owner counts. Stacks multiply the echo, so two casts double it.

Changes by version

  1. 8 Jan 2026Bug fixInternal playtest
    Necro Mastery power icon now properly displays its stack count

Internal playtest notes are from before the Early Access release. Names and numbers in them can differ from the game today.

Purchase today
If you haven't bought Slay The Spire 2 yet, it's time. Support the devs, they made an amazing game.Get it on Steam