Hmm interesting match-up, if I can recall I think Loki has actually tricked Mephisto at some point. Back to the fight, Mephisto takes it, he has too much for Loki but I wouldn't be surprised if Loki pulls something and wins it.
I think that this fight would depend on where it went down. If it took place in Mephesto's realm, he's win for sure, but anywhere else and I think Loki could take it maybe 5.5/10.
Gender: Male Location: Following the Source of Light.
Cosign. Mephisto has better showings than Loki. I mean, when is the last time Loki literally shook the cosmos when he fought someone? Loki might win some with trickery, but he'll need to be at the absolute top of his game.