I am unsure of which forum section to go to, this one or Gremlin Chatter, but thought it would be more relevant here.
I've tried quite a few times to finish this mission, instead myself and many other knights have used up much of our energy reviving ourselves repeatedly. Are there any higher ranked persons on here that could give some assistance or hints for this?
I've even maxed out the number of players (almost every run) that could help in missions and together we all still couldn't make it.
I don't remember the specifics of the mission, but Candlestick Keep can be a tricky place for less experienced players (and even for some of us more experienced types sometimes). The best general advice I can give you is to take things slow when you're in a lit area: stick to them like glue, and try to lure/bump enemies back to them, so you can take care of them without worrying about Grimalkins. If you're in an area with a candle that has to be lit, don't wait for it to go out before you re-light it; if you throw an ember at it while it's still lit, you'll reset the timer. If you ask around Haven, you might be able to scare up one or two people that'd be willing to help you; I wouldn't mind running through it with you myself if you happen to bump into me.
Send a message to Raisinfist in-game. I have a LOT of practice with Candlestick Keeps, so you can pretty much rely on me being able to revive you at any point you may die.
I have faced the same problem myself.The farthest I got was when I played alone.