Slifer the Sky Dragon

As additional cost to cast this spell, sacrifice three creatures.
This spell can't be countered.
Flying, haste, shroud.
Slifer has +2/+2 for every card in your hand.
Every time a creature an opponent control enters
in the field, deals 5 damage to it.
If Slifer the Sky Dragon enters the battlefield
from somewhere other than its owner's hand, sacrifice it at the beginning the end step.