Goblin Glutton

Haste, Incentive(Create X colorless Treasure artifact
tokens under your opponent's control, where X is equal
to this spell's mana cost.)
This spell costs {1} less to cast for each Goblin
you control.
Landfall - Whenever a land enters the battlefield
under your control, create a Treasure artifact
tokens with "{t}, Sacrifice this artifact: Add one
mana of any color."