I did this with a war, 3 mages and a priest. I had a bit easier time then velani, but still it is quite tough.

Basic strat is what I showed velani:

By the time you see the portal guard yell something "TIME WILL END BLAH BLAH" you have about 15 secs to run over, pickup the add that spawned and tank him.

With mages, I would dps down the boss hard, while thunderclapping hte adds. When whelps spawn, aoe everything till the welps die. Then when the portal guard is like 10%, aoe everything down. If you do it right, adds and guard die at the same time. Drink, and rinse repeat.

For first boss, just dps him down and kill the adds same way as a guard.

For second boss, LET ALL THE ADDS through, and kill him ASAP. Purge /Dispell the boss when it gets the haste buff (this will make it so your tank won't get overwhelmed by debuffs).

Last boss is cake, just keep your tank topped off, the boss faced away from the dps /healer, and have the dps/healer out of melee range.