https://everquest.allakhazam.com/wiki/EQ:AA_Costs_F#Finishing_Blow I'm not sure why the description, says it has to be fleeing, as it doesn't. It does work on nameds, so if your doing a quest or something where the mobs need to stay alive, it can be annoying. Basically, you have to quick attacking earlier (20-5%), turn you back to it, so you don't reposte it and trigger the effect, and finally use spells, if you have them for damage if it starts regenerating.
I'm iffy on it's value, in that it does cost alot to maintain it, and for most it ranks it only works on mobs 4-5 levels lower than you. I guess that means what level of content will you mostly be doing as to how valuable it will be.
Yther Ore.