Self-amputation and -mutilation is horrifying to me in a gut-punch, slightly titillating way. Kinda off-topic, but I'm trying to find a webfic that I read a f

Self-amputation and -mutilation is horrifying to me in a gut-punch, slightly titillating way. Kinda off-topic, but I'm trying to find a webfic that I read a few years back, about teenagers in a small town who become guardians of the forest (witches). One of them shapeshifts to kiss a boy she likes(?) The bit that really stuck with me was a dark ritual gladitorial tournament, where kids come back crippled, missing limbs, or dead. It happened at night in a liminal dreamworld, but the consequences were real. I think what gets me about that kind of thing, is that in the modern world most blood sacrifice is hidden. People pay in time and sweat, in long term health, and it's never as obvious as losing a hand.