Stoneskin as it exists right now is a superb deal. If the boss is a magic-type damage, you just use stoneskin to beat your way through the physical-damage monsters then you have wicked magic resist for the end-game.
Actually, just gave a run-through as Binlor-worshipping Paladin. Appears to me that 8 piety for 4% resistances is on its own an excellent deal, and if you have knockback attack you should have no problem maintaining enough piety to spam stoneskin before every attack on physical-damage opponents. Only issue is avoiding curse.