These are must have for Raid
Zytima can put healer's mark on enemy's Team using 2nd ability "Anger of Flies" which allow BloodPriest 2nd ability "Cry of Void" to do double damage. BloodMage can put a lot of debuffs on enemy team.
Kage gives extra attacks + anti-heal. Maedb reset speed, silence and poision enemy. SwampKiller slow, skip-turn and do a lot of damage.
Raarspit 2nd ability "Poison Squirt" deal 62% damage over 2 turns and put rogue mark on target which can follow by any attack by SwampKiller to do additional 40% damage over 2 turns => sure kill on a target after 2 turn.