My thinking is that when you're reinforcing your spells, you'll lose card advantage pretty quickly. This land would mean you can (mostly) always have a card in hand and one to reinforce it with. Should it cost mana though?

Yes, it should. Many red decks would play this even with no white cards at all (and so would some white decks, and possibly some green or black decks).

I think mono-red decks ought to be able to play this. I'll add a hybrid mana as the cost.

Yow. "Should be able to play" equates to "Every single one will run four copies"? Ok, ETB tapped, but to draw an extra burn or goblin every turn; who cares?

I don't think you'd run 4 copies in an aggro deck, since it's legendary. Probably 3 though.

I'd really advise against giving this the types "Mountain Plains" though. It's exceedingly strong, even without being able to search it up with a Bloodstained Mire.

Okay. I see what you mean. I meant that if you're a mono-red Otter/Eagles deck then you should be able to use the card.

I'll have to brainstorm another ability to offset the Reinforce ability.

Can this just be a bit more expensive to activate? All the reasons why it's an appropriate card sound persuasive. Any cheap repeated card draw (even with the requirement to empty your hand first) is likely too strong, but I'm not sure if the idea is wrong. (R and W don't usually get card draw, which is something to watch, but it's not completely impossible.)

Made it more expensive to activate and also more risky. You now have to ditch the card you have in hand and also risks a blowout by someone bouncing something, or not drawing anything good.

I don't know what this looked like before, but right now it's quite good. If it were mono-red I would absolutely out it in my Feldon of the Third Path EDH deck. This would go in every red or white deck, for sure. Compare it to Desolate Lighthouse for an idea of the power level.

@Link it was tap to draw a card if you only had 1 or less cards in hand. Then 1 hybrid mana for the same effect.