The 20 pt tooltip reads "5% assassination". I haven't noticed any added effect to Cold Blood or Backstab after numerous tests. Do mobs have to be significantly lower level than you like in EQ?

Hm, I'll have to test this out myself when I get a chance. Should work 5% of the time. Doesn't require anything special. Kills any non-boss instantly 5% of the time with cold blood.

I don't like the sound of that. Sounds to me like a 5% chance to abruptly end your chain. What do you think of another effect that's less RNG? I was thinking of something that would play into the crit theme of Cold Blood. How about +200% critical damage to the Cold Blood next hit effect?

Yeah, it's like this game evolves faster than I can re-design it (if that makes any sense). I'd like to re-design talents like this one.