Hellkite Peak

({t}: Add {r} to your mana pool.)
At the beginning of your end step, if you control three other Mountains and Hellkite Peak
isn't a creature, you may put three +1/+1 counters on it. If you do it becomes a 0/0 red Dragon creature with defender and flying. It's still a land.
Mounds, reasonably safe. Hills, probably fine. Cliffs, begin to worry me. Don't go near a summit!