Diglett's Cave

Diglett's Cave enters the battlefield tapped.
When it does, create two 1/1 Diglett tokens
with Dig tapped.
Diglett's Cave and each Diglett you control
doesn't untap during your upkeep.
{t}: Add {b} to your mana pool.
Sacrifice a Diglett: Untap Diglett's Cave and
each Diglett you control. Activate this ability
once each turn.