Any company moving to Mount Doom has its hazard limit modified by +2 and hazard creatures may ALWAYS be played keyed to the site regardless of any other cards played.
But there's the main reason to go there to consider. Since no items are playable, there's no excuse other than if you have a really, REALLY strong company and want to get lots of M.P.s for beating up Nazgul, to go there. But the reason to go there is a good one - winning the game is worth it if you have a powerful enough company, but otherwise you'll just be sacrificing characters to hazards. Destroying The One Ring is mostly a good playing strategy if you're either playing solitaire (I don't see anyone posting solitaire M.P. scores, do you?), if you have a deck you can get it done really fast in (lots of Precious Gold Rings, all the necessary sites, wizard's tests, and Scroll of Islidurs (it increases a dice roll by 2 for a ring test)), or if your opponent has lots of high-power factions and allies and you know there's no way you're going to win by M.P. If you have someone like Frodo, it's also a great strategy, though if you're using it for other things it's almost difficult to part with (you'll see how powerful it is when I review it in about two weeks). Overall though, Mount Doom is a card to have if you're destroying The One Ring and to get rid of if you're not.
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