Core-X

When Core-X takes damage, create X 1/1
X-Parasite tokens, where X is the total damage
taken. Those tokens have: "Sacrifice X-Parasite, {x}: Destroy target creature or exile target
creature from a graveyard, where X is target
creature's converted mana cost. Create a token
that's a copy of target creature destroyed or
exiled this way. Token is a X-Parasite in
addition to its other names and types and has
this ability."