Possibly too strong as a finisher? It's +2 for each untapped mountain, and you'll have at least 5 of them, for a 14/14. Very red to take the "If this gets through, I win, otherwise I lose" approach, though; and it lacks evasion or trample.

"+1/+1" looks very un-red. "+1/+0" is just so much more traditionally red; +1/+1 is green or black.

I like the creature though.

Um, yes. I don't know why I made it better than firebreathing.

I could really use space on some creature or other to explain the whole "+1/-1 implies 'on fire' thing."