Just do side quests until you get a powerful new spell. Then try again until you finally pass it. If you dont have side quests then battle some powerful bosses until you level
You might go to the Bazaar and buy some Death Shields. The 85% variety will help blunt the attacks. You might also buy some Storm Shields (get the 90% variety), as the most deadly spell each enemy casts is Storm Shark. Put the shields in your sideboard and use them on turns you use to wait for pips.
Take out the minion (the Grave Phantom) first. It hits just as hard as the Wraith does.
Keep one of your own minions active to help fight and to take some of the heat off of you.
