Vliadeth, Kethikara's Cradle

({t} Add {g}, {r}, or {b})
As Vliadeth, Kethikara's Cradle enters the battlefield, you may sacrifice three creatures.
If you don't, it enters the battlefield tapped.
"Just as you have bled so will the next,
just as you have bled so will Vli'Keth,
just as you have bled life reaches its apex."
-Vli'Keth proverb.