how to kill the ivalice guy and his crew.

Well...One thing you can do is equip auto-potions on the people you fear will die....Hmm...Have all your characters at the start of the stage...(kill the summoner) Since Izlude is gonna come right at you , you don't have to go to him. Just make sure you dispose of him with all your character's attack. Try to use haste at the start of the battle. Try to cast Ice 4 or any other level 4 spell on him( or even flare.) I don't rly have an exact battle tactic for him but.... I hope that helped. (Just a heads up : make sure you have a save file on step before every even you go to. Maybe you'll see why later on)( you might also want to make Agrias take care of those knights)