I'll just do a brief guide to HotW Explorable Mode here:
In General:
Dodge the rain of arrow aoe (big red circle on ground) from mobs; if you can, have your ranged dps down ice pillars (events) first.
Path 1:
Pull the first wave of mobs to below the stairs so you can LoS the ranged and bring them to you. Alternatively if you're brave souls, you can just kill them where they stand as well.
The rest is standard (you can skip a few mobs too), and then 1st boss. If you skipped the mobs before (going upstairs and jumping down instead of clearing all the way), you want to rush to the corner and just burst the boss down in that corner. The reason is, you'll pull mobs if you stand in the open. If you didn't skip and cleared the mobs, pull the boss back to the hall way so you don't aggro mobs above.
2nd boss = face roll unless it bugs. The mobs in front of him can be aoed down in seconds. If you're ranged glass cannon then watch his animation, he does 2 X aoe projectile about 5-10 after he puts down an aoe circle around himself, dodge those and you shouldn't take any damage at all. If you're melee, then dodge that said circle around him and you should be fine.
Final boss (the butcher). Kill protection totem (and remember to keep killing it, it respawns) and leave the other ones, The boss needs to be kited, and don't shoot any projectile at him when he does a spinning-reflect-projectile move. Use the pillars in the room to your advantage if you're having trouble.
Path 2:
The first wave is tricky, these mobs do whirl wind and hurts a lot. Kite them back to the stairs and remember to not get surrounded, dodge out whenever it looks somewhat dangerous because you'll die quite easily to the whirl winds.
Then it's face roll face roll, first champion is a push over, then you enter a room where there are two ice giants. You can skip the first ice giant by running along the wall to your left, or you can fight it: it charges a player and leave aoe circles behind him in a path, distance will keep you safe. The next ice giant summons ice elementals, who then summons tiny ice elementals which explodes on contact, have someone in your group (elementalist or grenadier engineer perhaps) aoe them down at range.
Face roll face roll and you're at next boss. Have a longbow ranger or grenadier engineer pull back the quaggans (don't aggro boss!) from 1500 range, burst down these quaggans near the water (becareful not to reset the fight by going to deep into the water). Then the boss himself = avoid his ground target aoe (which falls down repeatedly in one area, so if he targets you, chain dodge out of that whole area if necessary, don't just dodge one circle), and avoid his ice breathe (frontal cone attack, mid-ranged, so staying far away helps a lot). If you can't pull quaggans alone first and pulled boss along with quaggans, burst down quaggans first and just try to kite/avoid boss.
Next you go into the water and there are some adds to clear. If you've got engineers in your group and/or other strong professions under water, it should be faceroll. Otherwise, pull carefully and try to burst them down one by one instead of zerging a whole group.
Final boss = avoid his charge (animation looks like superman charging) and otherwise just dps him down.
Path 3:
First pull = same with path 1. In fact it's the same with path 1 until you go upstairs and encounter the puppies. Try to aoe kite the puppies and burst the rest down once they reach your group.
The wolf boss is next. Kite him around, and dodge out any red circles on the ground. From time to time he'll target you and the animation looks like he'll jump-charge towards you, dodge that as well or it hurts a LOT. Sometimes he'll do an aoe fear+immobilize, you can either use a stun breaker, or wait it out (unless there's a red circle right beneath you when you get immobilized, OR the boss starts walking towards you while you can't move, in those cases either use a stun breaker OR use an immunity skill to tank that one hit from boss/circle).
After that boss, it's some easy killing and you're then underground. The first wave of mobs = aoe them down, but don't get surrounded. They die fast but they kill fast too. You then walk past an ice field and kill some more trash, and it's time for boss --- Kill the two adds besides the boss first, and if you can't pull them separately, kill them first while trying to survive the boss. The boss himself has 3 things that you need to notice: He'll leap towards one of the party member and do a hammer slam that takes away 1/2 of your health, it's quite sudden so a bit hard to dodge, so you'd want to make good use of pillars in the room + stand apart from each other to avoid aoe-death. The second thing is that he'll slam the ground, and there will be red circles appearing in a line before him --- Dodge that one and obviously don't stand in red circles. The third is that he will become an ice block once in a while, dps down the ice block --- It can be a bit hard to target, so ground target aoe and/or melee slashes would work best.
After that boss, the next pull is tricky. A bunch of mobs will charge out into the hall way, if surrounded you'll die of a quick death. So the whole group should aoe kite them backwards as far as you need, and try to ranged-dps them down as much as you can. If you're not paying attention, likely you WILL die here.
Remember to take out the ice bombs along the way, and then you enter water again. Unless you've got a grenadier engineer (or more than 1) in the group, don't fight the quaggan in water, pull them out on to dry land and kill them that way. After a few mobs underwater, you reach the final boss.
The boss does 3 things --- He'll do an attack on you that take away 1/2 of you health if more, but he does this rather infrequently. He may also put a rock on you and force you to sink down, basically a stun. Most importantly, he spawns hateful jelly fish which swim towards you and then explodes, it's an instant death. Dodge the jelly fish whenever they're close to you, don't dodge too early because they'll just keep following you, dodge RIGHT when they're about to explode or quite close to you. If you don't have time/endurance to dodge, make sure to hit that jelly fish hard at least once or twice so that you'll be downed --- it'll die --- And you rally.
That's it! A very crude guide to HotW.
