ddrakhan, meva, parti, snow

use meva ult to cast invunerable shield on allies

then have ddrakhan cast her skill 2 to provide a barrier to all allies against bleed and causing show your loyalty which diffuses the single target damage she takes to other allies

when the boss runs out of the 3 turn shields, use snow skill 2 to inflict freeze on her

when the chest monster runs out of the 3 turn shields, slay it using an attack or chain attack and it will debuff the boss

finish up with supa kicka from parti ult which does ginormous damage

you can also just throw more healers at the problem since the boss isn't a problem once the mob is slain

mene can also be used instead of meva to revive the two front units and once they are revived they won't even have the bleed