Everyone is equipped with Physical Defense Down gems so that I can lower Abaasy's defense as much as I can (just Slit Edge and Worldly Slash won't do at this level). I managed to do it with Shulk, so 40% physical defense (default Abaasy's defense), -50% from Slit Edge, -20% from Worldly Slash, -25% from gems, total -55%. This and a long enough chain, and you can destroy the strongest boss in the game. Also first try.
