You run towards temple. Assess situation. If they have might+fana n stuff, may be beste to restart. If they are not all packed right inside the entrance, run inside entrance. Let them come towards you a few steps. Run down stairs. Re-heal you and merc. Run up stairs. If using war cry = Start stunning them, but be careful with distance, don't let them hit you, let them engage merc. You cast war cry from a foot away, but try to hit as many as you can this way. The unique bosses have only 10% chance of getting affected, yet it does work, if you have slightly faster cast speed, and high level wc, they will too be stunned most of the time, sparing merc lots of damage while he works.
This is the fastest way to kill them, when you get the routine down. Other than to hop around like a bunny boy.
And ... you can use amp charges on gavel of pain, i did that years ago be fore it got mainly known. Yet i got harassed for it :( But you can use that one on switch. 3 charges, but big area. Run up stairs, immediately cast 1 cast with amp dmg. Let merc get to work (that rhymes ^^) ... luck willing, he will defeat them in order and quickly, and not get slapped to oblivion, he can get stunlocked from too many physical hits. I.e. you can get overwhelmed. Which is dangerous. You cannot use war cry stun + amp at the same time, so this is where the balancing act comes into play.
You can stun them first, let merc take out a few, then amp the rest.
If you get this routine down to a tee, you can use 90% goldfind gear, even wealth armor. You will not have much resists or defense, but the key is to play footsies like a boxer, juuust keeping the distance, letting the merc do the work (again ^^) ..... while you play the good supporter. Then, as they start dying, you can simply start hoarckin them. N pick gear.
It's damn cool when you start getting the routine down in hardcore. Yet, complacency is the downfall of ... the lesser fortunate. Don't get cocky. Because it is the one time you think you have everything down, and let your guard down, that's when you get a pack of death lords which will throw lots of meteors at you, and fireballs, and you may take a collective large hit. Nasty things can happen within a fraction of a second. And don't get hit by geleb flamefinger. That is one nasty customer. Extra strong + fire enchanted - if he gets might, fana aura, forget it, don't get hit. He will send you into oblivion and the infamous ko screen. And you will regret it later. I once took about 1000 hit points in one swing. From about 1100 hit points to 13. I was shocked and simply walked away, waited 2 seconds before i could think, then saved and exit. Lol i was sooo lucky to survive. Sometimes you get a little luck........... and sometimes the luck on your bad side. I've had that happen too. It sucks ... but that's the game ;)