Zendikar

Indestructible, trample. Zendikar is a land.
Zendikar is not a creature unless there are 7 or more +1/+1 counters on it.
Whenever another land you control becomes a creature, put a +1/+1 counter on Zendikar.
{7}: Put four +1/+1 counters on target land, it becomes a 0/0 elemental creature with haste in addition to its other types.
{t}, Remove all +1/+1 counters from Zendikar:
Add that many {c} to your mana pool.