The Wraith is one of the most vulnerable monsters in the game to the BURNDAYRAZ glyph. With its low HP and reliance on mana burn and physical resist for survival, it's practically defenseless against fireballs and easy prey to any character skilled with them. Those trying to use melee combat will have a much more difficult time, dealing reduced damage and suffering the mana burn affliction. If you absolutely must make a physical attack, always try to use up your mana before attacking a wraith and try to do so shortly before you level up so that the mana burn can be cleared off easily. Using some form of First Strike to avoid mana burn is another option, which is particularly effective after using fireballs to soften up the wraith. Because you want to avoid physical attacks altogether against this monster, the BLUDTUPOWA glyph is particularly useful against it.
How to remove Mana burn:
The Tormented One, the Wraith boss, has much higher physical resist in addition to all the usual wraith properties. Spellcasting is the way to go here.