To help with raid groups getting stuck and burning out on bosses, what if vanthus runes applied like determination. You get to a boss, apply it. Cant kill it, no problem. Next week, get to boss, apply a second stack. Continue until you kill boss and stack clears.
It would not be an exact 1-1, as its one stat, but I could see it being a way for guilds to get through encounters that their comp/ability/gear get them stuck on.
It would still be earned, with clearing up to and then returning week after week to a boss.
Maybe you only allow the stacks to apply until X weeks into a raid tier, ect. But at some point letting more people kill bosses is beneficial.