Unbreakable Grasp is huge! This brings enemies to a crawl and helps line up AoE damage for myself and the wizard, while reducing damage and stress for our monk and barbarian.
SPLINTERS! For single targets, I don't think there is anything better. This move is practically free, deals 180% weapon damage, can be spammed, and of course can be buffed by Soul Harvest.
Now Soul Harvest is ridiculous as everyone else has been saying. When combined with equipment that adds to intelligence, your splinters can carve right through elites and bosses.
And I've only had it for a while now, but I'm really liking Acid Cloud. I replaced my exploding toads with this because the direction is consistent unlike the toads. For a while, I would SH then spam toads, which worked great, but spamming Acid Clouds over groups of enemies is far more consistent. I just can't wait to get some runes for it!