Syl, Terraformer

Flying, hexproof
Whenever Syl, Terraformer enters the battlefield or attacks, each player's land that isn't a Mountain is a Mountain chosen at random.
Syl can only be blocked by a creature with toughness 10 or greater.
When Syl dies, add {r}{r}{r}{r}{r}{r}{r}{r}{r}{r} to your mana pool.