Retaliate.

X is the strength of the abyss.

Forced - After Creature from the Abyss enters play, if the strength of the abyss is 2 or lower: Add 1 strength to the abyss.

Forced - After Creature from the Abyss is defeated, if the strength of the abyss is 5 or higher: Remove 1 strength from the abyss.