Thanos, the Mad Titan

Vigilance, Double Strike, Trample.
When Thanos enters the battlefield, search your library for an artifact named "Infinity Gauntlet"
and put it into your hand.
Whenever an Infinity Stone enters the battlefield,
you may attach it to Thanos, the Mad Titan.
Whenever Thanos leaves the battlefield, you may
pay {4} to return it to your hand.