Work Station

Send to the Mine — Sorcery speed: Choose up to three creatures you control. If each of those creatures is a Dwarf or has a Pickaxe, exile them into The Mountain.

At the beginning of the next end step, return those creatures to the battlefield tapped.

{3}: Create a permanent Pickaxe marker. (Choose a creature you control. That creature has “This creature can be sent to the mine.” Pickaxes are permanent and can’t be removed.)