Monk/Cleric/Sacred Fist or Monk/Dread Necromancer/Enlightened Fist
Have him pre-buffed with Divine Power, and alternate Touch Spells (Contagion, Poison, Inflict, Ghoul Touch, etc...) with Touch Spells stacked with Unarmed Strikes.
He'll have a good Touch AC and Uncanny Dodge, Touch Spells are...