Mend is a great spell for a book that is going for a mana curve. If you find yourself casting high level spells like level 3 creatures and up you may have a few mana left over. If you have some damage on you it can allow you to heal up just a little bit to make a gap of difference in the game. Also healing is more efficient the more armor you have, so if you go for a high armor mage consider mend to get rid of that 2-3 damage you might be taking a round.
I've been experimenting with dark mages and mend, it's not bad!