Yarnilyog, Mother of Mimicry

X= Converted mana cost of the target creature.
When Yarnilyog, Mother of Mimicry enters
the battlefield choose target creature.
Yarnilyog, Mother of Mimicry's power and
toughness become that of the target creature,
and Yarnilyog, Mother of Mimicry gains any
keyword[s] of the target.
If Yarnilyog, Mother of Mimicry dies, create
X 1/1 Doll tokens with those keyword[s].