I think a lightning mage wouldn’t be totally redundant. They could have extremely large range (maybe even global) but not a lot of power, and they should be somewhat slow, having to channel more than most.
- Lightning - like Azra’s, only no Psi cost per cast and a reasonable cooldown; possibly includes a short stun. Shortish channel.
- Storm - A storm cloud deals DoT over a few squares. Longish channel and cooldown.
- Chain lightning - hits 1-10 targets depending on level, short stun on all targets. Longish channel, medium cooldown.
- Tornado - travels either along path or, for simplicity, just in a straight line. Minor damage and knockback, long cooldown and longish channel.
- Current - channels lightning through a single target for a few seconds. Other enemies in the path take reduced damage, and it could possibly arc to some extent to make this happen more easily. At the very end, a final surge damages and stuns the target and damages nearby enemies.
This is sort of like a cross between Ice Mage, Archer, and Knight. In particular, stun and knockback are sort of rare and the only multi-target stun is a high-level Dragon skill, so Tornado is questionable. One possibility is that there could be only one of certain classes which would be open to abuse if spammed. However, this could be a class that’s really expensive to upgrade like Dragons… but even then, there’s no fire/ice trade-off to nerf them here.