Pick your poison:
Teleport his Priestess into a Spiked Pit and hit him with a Hydra a billion times?
Keep him Jinxed or Tanglevined with an Astral Anchor?
Whirling Spirit through a Wall of Thorns?
Run a Deathlock?
Use the lightning Ring, Hawkeye, Marked for Death, Enchantment Transfusion and Arc Lightning on the angels.
Combine some/all?
Not sure what's going to fit your cardpool or playstyle. What's the biggest trouble you have with Guardian Angel and what's your book's kill method?
Edit: Also, I've found that Tanglevine on the Guardian Angel is very helpful as it takes several actions or a precious teleport to free her.