Isn't that save based on received damage? Fluff wise if not directly...he will eventualy roll low or 1, but I think he has high enough fort that you should use other powers instead of waiting for that to happen.
Whatever you do, do it fast, on Marius' turn he'll retreat out of reach (for a round anyhow)
hellrazor, I checked, initiating a maneuver does NOT provoke AoO. So the maneuver I mentioned earlier would work without Makuna's attack. Unless you rule he detects Marius straight up and can prepare accordingly...