Soul Egg of Koscheiy

While ~ is on the battlefield "Koscheiy the
Deathless" is a creature whose toughness cannot
be reduced below 1 and cannot leave the
battlefield.
When ~ enters the battlefield create a 3/0 black
Human Immortal creature token named
"Koschei the Deathless" with Deathtouch and
Indestructible.
When ~ enters the battlefield attach it to target
creature, land or artifact you control
until that leaves the battlefield.