There is an unfortunate glitch in Level 1 where the mage necessary to beat the level sometimes doesn't appear. I mistakenly set the mage to appear "at the end of the enemy phase, if exactly 3 enemies have been killed" so it's possible to kill two enemies in one turn or for an enemy to die from Onyxia's counterattack and bring that 3 up to a 4 before the enemy phase ends. Hopefully this doesn't crop up too often, but if it does, just try again. I hope you enjoy this game regardless.