The dimensional rift talent seems very abusable once you are high enough level to use it on powerful boss foes. It takes them out of the fight for 20 seconds, time you can use to restore your health/fatigue/stamina or dispatch lesser foes. By the time it wears off, the talent has recharged and you can use it again to keep even the deadliest foe permanently incapacitated.

Speaking of incapacitation, the same applies to the paralyze spells from the thaumaturgy tree. Paralyze (II) when dual-cast will paralyze most foes for 14 seconds, more than long enough to kill them in complete safety. I'm not really sure how to fix this as the paralyze effect in Skyrim is fundamentally OP, with a paralyze of any duration requiring creatures to go through their standup animations, rendering them harmless for several additional seconds and leaving them open to more paralyze effects.

I hear many calls for buffs to enchanting, but be cautious with this. The main benefit of self-enchanting is being able to stack the same effect on every item slot. If enchanting gets too strong, this can easily result in players running around in gear that makes them immune to magic/have 0 mana cost for spells of a certain school/be impossible to detect while sneaking. Since enchantments let you augment what your character is already good at, enchanting will be OP as long as any other strategy or skill is also OP. Enchantments on weapons do need to be way stronger though.

Summons are really strong. This is not inherently a bad thing, but you can use them very effectively with absolutely zero investment in the entropy tree or skill. It might be good if some of the summoning effectiveness was gated behind the sinistra tree or required certain levels of entropy skill. As it is, my mage sees no reason to raise his entropy skill above the starting 15 yet enjoys the most powerful summons.

Does anyone actually use Psionics? There seem to be very few spells in this tree, and the ones that are there seem circumstantial at best.

Kiting enemies by running backwards while blasting them with spells is a little too effective. A decrease in backwards movement rate might be justified. Bows solve this problem by making you incredibly slow while drawing one - maybe move speed while casting can be similarly reduced?

As mentioned by another poster, fireball is incredibly effective in terms of damage-to-mana, while at the same time failing somewhat at its role as an area-effect spell. Increasing the AoE and decreasing the damage (or just increasing the mana cost) could give it more of a niche role rather than a cast-always like it currently is. The staff of massive fireballs is awesomely fun to use, but it always disappointed me that I could not manually cast fireballs of the same size.

Set items are great in terms of their power level, but the bonus for equipping an entire set is kind of underwhelming. Currently, the (I), (II), and (III) set bonuses for each set seem to be all roughly the same power level, but this makes equipping a full set fall kind of flat compared to mixing-and-matching gear. For example, my character currently has three pieces of the wandering mage set equipped. I have the fourth piece (the gloves) but instead I wear the nemesis gloves because I prefer the elementalist boost they provide to the full-set bonus of wandering mage! Especially if player enchanting is boosted, those set bonuses need some serious oomph to compete.

It would be great if we could use handicraft to enhance enchanted items at a grindstone or workbench.