City Portal (as mentioned before, for tactical retreats), Hypnosis, Illusion (helps avoid that retreat by overwhelming the enemy with clones; their loss doesn't affect "losses during the retreat" as much), and Clairvoyance (if you know who to attack and won't have to retreat).
Everything else is secondary. I primarily use the spells mentioned above, and also shoot with Ice Bolt.
<edited at the request of Pandora>