In my experience voltaric shield is the reason why wizards are the most powerful of all mages. Builds who focus on attacking the wizard early have no chance at all, because 2-4 armor+voltaric shield+regrowth let him survive everything in the current meta. Curses could be a threat, but as a wizard dispel/nullify/mage wand are so cheap that curses are no matter as well (I had enough games against good warlocks).
Sure, the voltaric shield is gone after the first attack that deals damage, but with some armor on you, low dice attacks have a realistic chance to not deal any damage at all. In the worst case, the shield absorbs 1 damage, which still is important in a damage race and 2 mana for 1 hp isnt that bad if u consider that you did not use an action for it! Anyway, with my build I have enough creatures to focus down the sources of low dice attacks quickly. Therefore, the opponent is only left with high dice rolls, against which the voltaric shield is just awesome. I had so many games in which a hurl boulder did 0 damage because my wizard had 4+ armor and all crits were absorbed by voltaric shield.
@Zap: Its not nearly as great as voltaric shield, but still very useful and I think everyone who played the wizard knows it. No need to explain further.
IMO these two innates are the strongest abilities from all mages except the Forcemaster. Deflect can be better or worse than voltaric shield, depending on situation. The same applies for force pull and zap. What makes the wizard so incredibly powerful that I never lost with him for many games, is the combination of awesome innates, arcane school, an elemental school of choice and no opposing school! Arcane school has cheap access to most of the mandatory spells and in addition the wizard tower, a great spawnpoint and some really nice creatures (hydra, gremlin, gorgon archer, gargoyle). Sure, nature has better creatures and better enchantments; dark has nice creatures as well and awesome curses. But still, many good players consider arcane school as the strongest.
So what else does wizard have? Oh yes, an elemental school of his choice. Cheap golems+hurl boulder. Or cheap fireballs etc. With the current meta, even water works great because dissolve, surging wave and geyser are awesome spells in the right situation (with the expansion I guess water will become the strongest wizard).
Last but not least, the wizard has no opposing school.
All these strength add up and make the wizard the most powerful mage of all currently available. Actually, I would go so far and say that an elaborated wizard build has a chance to win of over 80% against the overwhelming majority of non-wizard builds (maybe even all non-wizard builds). There might be some specialised builds that can scratch the 50% win chance mark against an elaborated wizard build. But, those builds will be so specialiced that they have no real chance to win against most other builds.
In the end, im really curious about the new mages. They might re-establish the rock-paper-scissors environment that is needed for a healthy game.