Guilds should be able to pick a "theme" and be viable in group content without relying on nature or the light.
I said it.
If you wanna make an emo guild full of void elf death knights and warlocks, you shouldnt need to invite a hippie elf, drunk panda, or white-robed gnome to every Mythic+.
Solution 1: 4th spec somewhere. Soulstone Warlock, Necromancer Death Knight, Shadowmender Priest.
Solution 2: "Gladiator" styled talent for an existing damage spec to allow them to heal instead. Shadow Priests, Affliction Warlocks.
Solution 3: Necromancer or Alchemist class, obviously.
I excitedly await your comments, concerns, and ravenous support.