How to Complete Escort Wanted

Your objective is to prevent Thamas from getting KOed, and defeat all foes. The foes are a Deathscythe, which is weak to Holy and can be killed with moves like Exorcise; a Lamashtu; and a Headless, which is weak to Wind. The Deathscythe and Lamashtu can cause Doom, so you can equip someone with a White Staff and hit people with it to remove their Doom status. The Lamashtu can inflict sleep and Doom on all units with its Eternal Sleep move.