The spells you are not using correctly...

[DragonSoundxSG]

1. Night Comet - off-hand the Staff of Loss for +30% damage; off-handing applies to other +% dmg staffs or seals as well when casting the appropriate spells.
2. Rykard's Rancor - yes it's annoying if spammed, however it's uber powerful at point blank range on large enemies it can wrap it's fiery tail around
3. Crucible Knight incantations - benefit hugely from wearing CK armor (+3.5% dmg per each, so realistically +10.5% (3 pieces) or +14%(!!) for 4.
4. External Darkness - if you're a PvP Mage (or fighting Loretta), you should be at least giving this a try. Only caution - Night Comet bypasses it.
5. Black Flame incantations - do a lingering % of damage and are therefore are powerful against enemies with high HP

[PK_Thunder]

Ancient Dragon Lightning Strike. It's so busy visually that it isn't easily apparent that it's not just a point blank AoE. It has slightly larger range than the basic Lightning Strike you get in Weeping Peninsula.

Vyke's Dragonbolt. It was buffed to have the same scaling as the two spells it mimics, so not only is it not bad anymore, it also looks damn cool.

Any AoE healing spell will do enormous damage to Revenants, and stun them for a while.

Stone of Gurranq can be chain cast until you run out of stamina.

[cridus]

great oracular bubble: equip the arrow's reach talisman, unlock, look away from the target, start casting and once it's too late for the character to turn around, lock on. it will make a large circle to reach the target. if you play it well and reposition, you can hit people from behind and combo stuff into it/make it combo into stuff.
(all credit for this goes to Mahqez from youtube)

the arrow's reach talisman works for a few other spells too. one is rock sling.

death lightning: when I used it a few patches ago, it was super good at hitting people in melee range. like, start casting it (uncharged) when they're approaching you and they will get hit most of the times. will oneshot anyone who doesn't level vigor very appropriately, especially if you use the gravel stone seal(s) and buff lightning damage with the physicks, + eventual incant-boosting talismans.
I mentioned the fact that I did this a few patches ago (3 at most, iirc) because last time I tried it in the arena I've barely hit anyone... but I have a lot of footage of me oneshotting people with it from back then.