Eine Kreatur deiner Wahl, die du kontrollierst, fügt einem anderen Ziel deiner Wahl X Schadenspunkte und sich selbst X Schadenspunkte zu, wobei X gleich ihrer Stärke ist.
If the target creature you control is an illegal target as Self-Destruct tries to resolve, the creature you control won't deal damage. If the creature you control is a legal target but the other target isn't, your creature will still deal damage to itself.
The value of X is calculated only once, as Self-Destruct resolves.