I said I "think" you can use slow, maybe it is immune to them all.
Sentinel is VITAL BTW, use the paradigm.
EDIT:
to elaborate the sentinel will draw attacks from the proudclad to itself, meaning your characters with less HP survive, you can continue building up the stagger meter and the sentinel has moves that can automatically regain its HP while its being attacks
but have you developed the role on the crystarium? If you haven't you might not have some cool moves in the role.