Before you start, Auron needs Provoke and a Berserk Ward armour.

Position your characters one tile apart so the Keeper's physical attacks only hit one character. Cast Protect on Auron and have him Provoke Spectral Keeper. The Berserk Ward will stop Auron being inflicted with that status. Attack with Auron and another character while the third heals Auron.

If the glyph mines appear under your characters, summon an aeon to take the bullet. It's good if they have an OD to use before they get blown up. Reapply Protect and Provoke as necessary.