Steve, The World Crafter

Yearn for the mines — Whenever a basic land
you control adds mana, add one mana of any color added, then place a mining counter on it
and create a treasure token. Your basic lands
with 3 or more mining counters on it becomes
a colorless land with "{2}, {t}, Exile this land:
Draw a card." and loses all other abilities.

Steve, The World Crafter has power equal to the number of mining counters in basic lands you control.