Quote Originally Posted by Nidgit View Post
There's nothing that says you lose concentration when you hit 0 HP, though, and Faithful Summons 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.
Interesting. By RAW, you are completely correct.

Other than ending it manually or failing a Concentration check, Concentration ends "Being Incapacitated or killed. You lose Concentration on a spell if you are Incapacitated or if you die."

Whereas Wild Shape specifically says "You automatically revert if you fall Unconscious, drop to 0 Hit Points, or die." So "If you are reduced to 0 hit points" as it states in Faithful Summons while Wild Shaped, you will revert back and trigger the Faithful Summons with the only downside being a Concentration check for the taken damage assuming you dropped to 0 hp by taking damage.

Nice catch on that. Very useful.