Or when you take on a named that "could 2 round you" you could be using a wizard merc instead of a cleric, and use a defensive disc + epic/Vod/Scarlet and Win before any of that wore off, without the need to incessantly mash your tap multibind. Atleast thats how I molo'd hunter in WK/Neriak (other then Gelden), No willsapper required. Although if your squishy like Aste said I will admit Willsapper might come in handy for the rare occasion you can't heman your way through it. The cases where Willsapper could make a loss into a win though are few and far between at best.
Killing a single named target, deflection, and the defensive disc, and spire along with your 2.0 and zombie mode will keep you up. For that one target. But to kill red cons continuously back to back, that are a good 5 levels over a normal yellow/red con group trash mob, you will want to land slow. I have gotten even tougher, and fleshed out additional aa's, but initially it can be hit or miss for a level 86 to molo upper house of thule mobs in basic group gear. And when you are killing a hard target, procing slow can turn a dicey fight into something you can almost afk during as your cleric merc heals you.
your talking about a scenario I wasnt even addressing. Fighting upcons while under geared/aa'd is totally different, after Bout 70 its also highly inefficient as a means to XP. I guess you beat me though in your scenario (realistically one you shouldnt even be entertaining) sure slow had a ton of value, but your going to lose so much time by doing that. Work smarter not harder dude.
With high combat effects slow can proc really quickly, I have had it proc as fast as I can change targets and hit a bandolier key. If its smarter to kill 1000000 light blue cons that drop nothing but a little cash loot, when you could kill things deep red con that drop gear you can use now or for a long time, I guess I do work stupid.
Yes actually it would be more efficient to level faster to catch up your AA/level to further marginalize the content your trying to get gear from, 4 or 5 levels + afew thousand AA's vs trudging through the content slowly undergeared and under AA'd... Bet ya them extra 4 levels of CS/CA, TOTC, SA, TOL, Crit AA's etc etc will be of more benefit then Willsapper. So yes you are working harder not smarter. If your just doing it for kicks whatever or because you want to take the hard road whatever, but lets not pretend like its anything other then the scenic route. EG: If you were swarming efficiently at 86, you would gain roughly (this is alittle memory, pre Huge AA bonus) 45 to 60aa (guessing if your low on AA it will be alot more then that) an hour, and roughly 20 to 25% of regular experience. Given an average play time of 3 hours a night your going to have accomplished in a week, what will more then likely take you 2 or 3 weeks camping gear. Then with those new AA's/Levels you will be able to use better gear you can buy in bazaar or have a much easier time camping that which you want. Will take you alot less time to get what you do want and the risk will be much less (IE: less Ooops I wish I would have... deaths)
I think the last time I used willsapper was on a named in korafax. Low dps meant a long fight that the merc had to heal through.
