Void Spawn

Flying, cloning X (When a creature with cloning
enters the battlefield, create X copies of it, except the
tokens aren't legendary, if this creature is legendary.
Tokens created this way doesn't have cloning).
Tap five untapped Void Spawn creatures you
control: Create a non-legendary Void Spawn with Flying and cloning 3.
Sacrifice twenty other Void Swpawn creatures: Trasform in Asremas, the Voidlord.