Well, warlock got multiclassing and also feat which gives +2 bonus to will saves and has wisdom 14. Also turn ends when DC goes +1 above your will save (taking 10). So if got will save 7 you last 9 rounds (one DC 10 round and then round where you fail when DC is 18 is counted for endurance). Also some contestants have circumstantial bonuses vs school (arcane warrior played most his saves with hexblade class feature; arcane resistance).<br/><br/>Also force of personality is in play with some charisma based casters (using charisma instead wisdom for will saving throws).