Dont max mages. only one point will suffice. so:
Max Mastery, mages, poison nova, poison explosion, one into all other summons skills, one into the good curses (up to decrip, iron maiden, if pvm maybe confuse etc.)
Then make sure you get 1 into bone armor, and all extra points i say into poison dagger to boost poison nova dmg.
Bramble > Fort on a merc as dash said.
also, the multi aura stack, just pwns. you should try it out. just tele onto a monster, and epk. plus you never die.
Here's my guide, and feel free to ask questions or pm or whatever:
http://www.rpgforums.com/forums/showthread.php?t=70238
(it needs some updates, so some things might be off).