Quote Originally Posted by Nidgit View Post
There's nothing that says you lose concentration when you hit 0 HP, though, and Faithful Spirits doesn't require you to be incapacitated either. Normally reaching 0 HP causes Unconciousness, which then causes Incapacitation, which breaks concentration. Wild Shape specifies that you don't go Unconscious unless the damage you take pushes you to 0 HP in your humanoid form, but does say you revert when you drop to 0 HP while Wild Shaped. So you should hit still hit 0 HP when knocked out of Wild Shape to activate Faithful Summons, but you're never Unconscious or Incapacitated to break Concentration. You just have to make the saving throw as normal.
Oh, I see. Sorry, I misunderstood your point. I forgot about the first condition, "If you are reduced to 0 hit points or are incapacitated against your will..."