Brushfire Elemental

Once a creature with power 3 or greater has blocked this creature, changing the power of the blocking creature won't cause this creature to become unblocked.

A landfall ability doesn't trigger if a permanent already on the battlefield becomes a land.

A landfall ability triggers whenever a land you control enters for any reason. It triggers whenever you play a land, as well as whenever a spell or ability puts a land onto the battlefield under your control.