the team i used to clear this in normal difficulty is
front:
Attack succubus on energy drain/sensation
Attack lamia on lust (lust turns the lamia into an unkillable offensive unit like devils incarnate does to the imp)
Middle:
support succubus on cupid (if you use support succubus her skill only activates if you hover the bat over the succubus when her ult is charged, it turns the bat into a massive nuke that stuns enemies)
attack harpy on high pitched note (extremely oppressive support skill but might miss point blank)
Back:
Support lamia on poison swamp (extremely oppressive support skill but it might miss on mages hovering too high)
Support dryad on nurture (nurture is strong because it regenerates skill meter for one character by 70%, regens health and buffs damage)
all of them have pan in the back equipped, this item decreases damage taken by 99% (effectively its immortality) when the character is staggered by an attack, since the mages attack and stun your troops alot i think the pans might be the trick to beating it
if you have the Imp i believe shes better than the atk lamia for the front since she can attack airborne enemies (she can also use dark shield to cover your troops or use devils incarnate to ignore attacks herself and murder enemies without interruption)