Alright! I was able to do it without too much difficulty after taking your advice.
Character Link: Under Profile
Guardian/Adventurer: X Guardian
Build: BeastMage 100 INT DEX CHA, 150 LUK
Weapon: Zealot's Wrath/Solar Flair Staff
Armor: Sweater Dragon Mount
Shield: Ultraguardian Shield (Neutral element)
Pet: Unlucky Rabbit (multiple hits) and FGM for healing or damage when I don't have too many Haunted stacks.
Guest: Solar Angel
Misc: Lohkaista, Mana Trap
Potion: Shining Aura
Started off by using Zorbak's Ally Assist to turn him undead, triggering Shining Aura. Then, I used the Solar Flare staff to summon the guest for healing. Cast Gandolphin every turn to keep up the mana shield, and pretty much had to drink a mana potion ever other turn or so to keep it up. Used Sweater Dragon Mount in dismounted mode, but stuck with Zealot's Wrath for my weapon. Attacked whenever I didn't have to quaff a mana potion and switched to FGM pet whenever he failed to stack Haunted on me for a turn. The Ultraguardian shield gave me enough extra SP to keep the Solar Angel guest active the while time, while still alternating between Lohkaista Shard and Mana Trap. The occasional extra hits from the Sweater Dragon's breath attack really helped with damage output, and I didn't actually notice any problems with using Zealot's Wrath due to being in an FD armor.
I used almost 20 mana potions, but only 2 health potions. Success!