See Challenge # 157. When brainstorming for mechanics I had something similar, and I think this fits the Monks of Zhirs constant betterment through pain (and maybe even self flagellation) quite well. Could also work as a triggered mechanic with different abilities.

Nice. I was going to say that the cost might not be necessary, but then I realized that it would get easier and easier for this survive to reach its trigger.

I like the flavour and the concept but I'm worried this has the same problem a lot of "when this is dealt damage" and "when this deals combat damage to a creature" abilities, that it's a bit like "don't chump block this, don't attack into this with a smaller creature", which is probably what your opponent was avoiding anyway, so it may rarely actually have an effect.

Yeah, but I don't think that is that much of a problem. Mechanics that are slightly dependent on an opponents behaviour are considered bad, I know, but this just let's you play aggro. Go in the face, all the time, use damage spells that hurt all creatures on the board, try to accumulate counters. You can only ignore creatures hitting you for so long.