Changing Taunt is not a very good idea imo. Tanking in the traditional sense is not quite possible currently, since the AI is smart enough to not attack a character that looks like a damage sponge, and if tanking was possible the game would be much less fun... but that doesn't mean we just have to accept the fact that the AI will target our mages/archers...
The enemies usually target my dual weilding mage, so I use Leadership, Guardian Angel, Shackles of Pain, Erratic Wisp and Uncanny Evasion to great effect, but I doubt that alone explains her survivability rate (she didn't die at all since she drank the Blood Rose potion at the end of act 1, now she's level 19). She's a mage, so her magic armor is very high, enemy mages can't deal with her; any melee oponent has to survive her Flaming Tongues and Medusa's Head (they rarely do, those spells are insane even in low levels) and archers have to out-damage her Heart of Steel and Fortify, if they manage to get close to doing so and they're still alive, they'll have to rage quit after the Bone Cage scroll. My dual weilding mage is a pyro-geo-poly Lohse with very high wits, so she's usually gets to go first and decide if it's better to blow people up or prepare/prevent to be focused. If she doesn't go first and someone manages to cc her, the rest of the party will ensure her survival with buffs or plain retaliation.
If the AI happens to go second and see a buffed mage, they'll have to pick between a very tanky SS poly-warfare warrior, a high Dodge necro-scoundrel rogue and a tanky wand/shield undead support mage. They can't win, they can't focus fire effectively
