Rehexin, Hoard Wurm

Reach, trample.
At the beginning of your end step, tap all
untapped lands you control. For each two lands
tapped this way, create a treasure token.
If at the beginning of your upkeep you have no
treasure tokens, Rehexin, Hoard Wurm cannot
attack or block.
Once a mighty and noble dragon, Rehexin's downfall
came about when he tried to rob a wizard. Now
reduced to a state of mindless greed, he sits coiled on
his mountain, waiting for travelers to rob.