Erase is helpfull to have for pvp and sieges. But Mana Burn is a wast of time IMO. Doesn't seam to do enough vs. mages. Haven't tryed it much on archers or daggers. But if your lucky to get one of them 1vs1 you might beable to burn up all there mana. Just sleep/trance - mana burn - sleep - mana burn. How ever, I don't think this will work with mages, since mana burn does not take off that much MP. You will be out of mana about the same time your able to drain all the mana out of the mage.