Ancient Hydra - 'Bullet Hell!' - Charge the Dark Pedestal first, then charge the other 3 (Ignore the Dark Pedestal to skip VX mode).
M'Karsa - 'Holy Crab!' - Insert the rune into the fiery brazier before M'Karsa destroys it (Hint: The rune is located near by, but not inside his battle area).Tal'Navi - 'Rollin Rollin Rollin' - Never kill a Living Boulder during the fight.