What did Merlin do to Lancelot in 4x09?
*SPOILERS for anyone who's happened not to reach that point yet*
In 4x09 "Lancelot du Lac" when Merlin was sending off Lancelot's shade in the boat, what exactly did Merlin do to Lancelot to make him awaken briefly and say thank you? It was obviously a spell, but does anyone know what kind it was? Was he actually brought back to life for that brief moment (I'm thinking this is unlikely) or was it a spell that allowed Lancelot's actual spirit to speak through his shade? I don't think they made a reference to any such spell in that or any episode, or if they did, I totally forgot.
Edit: So I looked it up, which I probably should've done to begin with, and it says Merlin's spell set Lancelot's soul free so it could rest. So it was his soul saying thank you (through the shade) before departing to rest again.