Respect Your Elders is a lot easier now that he only spawns the one Guardian - have an off-tank drag it to the opposite end of the long corridor-room the boss is in, but make sure he's within healing range still. They have to be careful to hold aggro without doing too much damage, as the add dies quite easily. Once he's far enough away, the boss stops being immune and can be burned down, nice and easy!
Zombiefest has a nice and easy trick to it: when the second boss of Strat appears, drag him into the room where the Infinite dragons first appear, and don't DPS him. Have someone look out into the streets you came from, and when they see plenty of zombies respawning, you can kill the boss. You then proceed as normal through the bit with Infinite dragons, until you reach the gauntlet. Then send a couple of DPS back (preferably one with healing capabilities) to the first streets, while the tank, healer and a DPS stay at the gauntlet. When both are in position, the group of three starts taking the gauntlet, and the group of two starts killing zombies in the first street. Any zombie kills in the entire zone count for the achievement, so if both groups move quickly, it's nice and easy. It's even possible to do it fast enough to still get the fifth boss and drake drop!
Less-Rabi is the hardest and most frustration (in my opinion), as it's largely luck-based. All I know is to have as many people in the group with interrupts and the
Bitter Balebrew Charm equipped as possible; normal DPS and interrupt the first couple of casts, then everyone pop the trinket and nuke as hard as possible, blowing cooldowns when he's at 35-40%. Past that, it's mostly luck. Hopefully the Dire Brewmaidens will interrupt for you when it's too fast for normal. Also, once you get to the stage where he's casting too fast to time an interrupt, just spam them on cooldown and hope for the best.
Abuse the Ooze is quite easy: you just have to make sure people are spread out to avoid the boss's AoE stuff (mostly just to help the healer's mana last). Oozes come quite often from opposite sides of the room. When the touch, they form a bigger ooze, which you kill for achievement credit. Don't DPS the boss until you've killed enough for the achievement, as once he gets to a certain % health, the oozes stop coming and Earthen come instead. Takes time, but not too hard.
Dehydration is a faceroll: just use one of the crystals around the room each time he splits. The big purple lightning will kill all the adds nice and easily, although at least one person should be ready to kill any adds that get too close to the boss before the lightning kicks in.
Experienced Drake Rider doesn't really need anything to be said
Ruby Void was tricky, and I think in the end we did it with three Bronze and two Green; Lonny or Tbone might remember for sure, but I think that was our setup. VERY careful timing of Time Stops was critical, as was the Green drakes taking it in turns to use that ability that does a load of damage and reduces the boss's damage output. I say take it in turns, because it does self-damage as well as a LOT of aggro, and you don't want too much focus on your healers. If memory serves, this one is easier than Emerald Void, at least.
That's all I can remember from doing them: good luck, and enjoy your Red Proto!