[Taqwus]

I doubt that it'd do anything, actually. It likely needs to be from a spell effect that gets cast at the beginning of battle, and not an always-on effect.
There aren't that many, IIRC; most auto-casters are either summons or battlefield enchantments (storm, battle fortune, life after death, light of the northern star etc). Items like the copper breastplate would do this because it autocasts a self-spell instead of being always-on.