I hope it's a Magical Mitigation type soul that syns well with Stormcaller/Warlock
Air/Death type soul that takes damage and redirects it to mobs/mana while buffing the DPS of your attacks. Sort of a force multiplier that will let players play something in good conscience besides a Pyro variant. because really fireball spam is getting a bit old..
Air Death combo would also allow it to sin well with Dom and Necro.. and really if done right tie in the rest of the Mage souls in groups.. Storm/Warlock/Necro/New Soul... Pyro/Warlock/Archon/Element
With Chloro and Dom as Free agents spicing up the mix...
Chloro/New Soul/Warlock... or Warlock/New Soul/Necro Could add that "Tanking" mage people have been looking for.. (Though how holding aggro is going to work I'm not sure..)
Magical Mitigation or "Spell Armor" for damage absorption/redirection is really the only real area mages are lacking in it's like the Devs forgot that Magic would be researched for anything besides blowing things up in their world (Our short duration/long cooldown shields are okay but they under perform when compared to other callings) And I think it would be cool to add the "Hulk" factor to a mage.. Add a scaling buff that up's the Spell Power the more damage they absorb..
or in lieu of that A Teleporting Highly Mobile Soul would be nice a "Riftstalker" for mages that buffs def and life Just my hope