Burrenton Forge-Tender

The static keyword and the sacrifice clause are two different cards wearing the same 1/1 body, and you only get to spend one of them. Protection from red, left alone, makes the Kithkin a passive thorn: red removal cannot target it, red creatures cannot block or be blocked into dealing it combat damage, and a red deck has to find a non-red answer or route around it entirely. That mode keeps the body alive and does nothing for anything else you control. The free sacrifice ability inverts the whole proposition. There is no mana to find: you spend the creature and prevent all the damage a single red source of your choice would deal this turn, not the entire red board, but whichever burn spell, sweeper, or attacker matters most right now. Because the ability chooses a source rather than targeting a spell, hexproof and other targeting hatches do not enter into it, and the chosen spell still resolves: it simply deals no damage, a cleaner outcome than a counter for an effect that costs only a 1/1. The point is the instant-speed window. You hold the answer up and fire it in response to a spell already on the stack or during a damage step already declared, so the body is sacrificed as a cost and the prevention shield is set up to catch the damage before it lands. The trade is the design's whole argument: wall mode and one-shot-shield mode cannot both happen, so you decide each game whether the 1/1 sits still or detonates at the red threat.