Use fire spells on the zombies. They spawn poisoned ground when they take damage, which if it spawns on burning ground will instantly detonate to damage them. Casting a small fireball on a pack can instantly destroy all of them, or destroy them when they attempt to move out of it next turn.
Use protection spells or summons to absorb the CC/spells from the ranged enemies.
Buy scrolls if your characters can't cast spells.
