Driller, Cavern Dweller

Unblockable, Vigilance

When Driller, Cavern Dweller enters the battlefield or attacks, Explore, then you may put a land card from your hand onto the battlefield

Others Dwarfs you control have "When this creature attacks, Explore"

Whenever Driller, Cavern Dweller attacks, after combat transform Driller, Cavern Dweller