Great Wyrm Ixendaar

+2: Until end of turn, Great Wyrm Ixendaar becomes a legendary 6/6 red Dragon creature with flying, indestructible, trample and haste.
-3: Target land loses all abilities and has its names changed to Wastes. It gets "Tap: Add one colorless mana to your mana pool."
-10: Destroy all lands you don't control. Ixendaar deals damage to all creatures you don't control equal to the number of lands destroyed this way.