actually the dru and bard can boost either melee OR casters. so
your SK,Dru, Shm, Brd, 2x Zerk is viable
BUTTTT>>>>
so is
Sk, Dru, Shm, Brd, 2x Mage as dru debuffs and dots and nukes work well with mages, Shm dots/nukes work good as well and bard can be setup to twist caster songs