She kind of outs herself in the bathtub scene as a snake oil salesman... had she not given birth to a demon that assassinated someone, I would think her all smoke and no fire.
I still have this weird feeling she's a trickster. But apparently there's actual power there somehow. Certainly an interesting character.
She admits to using lies and illusions to guide people to the Lord's truth. Whether it really is the Red God, a mix of old spells & curses, or some other force I can't be sure, but it's undeniable that there's a higher power at play. Given what we've seen and heard from other characters I'm inclined to believe the Lord of Light is indeed a real deity who aids its followers.
Assuming Melisandre's blood curse with Gendry and leeches did what she claimed, in the War of The Five Kings she brought down three of them -- four if you count the end of the Greyjoy lineage when Theon lost his favorite toy.
That Stannis shadow baby was the single most wtf moment in all of GoT. It just pops out of that lady, goes and kills Renly and then disappears? Not only because it's completely unexpected, but also because no one ever talks about it. Stannis doesn't show any regret about Renly either, nor does he ever ask the Melisandre what the fuck happened.
Also, there needs to be more tension between Ser Davos and Melisandre. I loved it in the past season. Davos is the only noble person in Stannis' circle.
Yeah it was fucked up. He did show some remorse over Renly's death, though. It's actually in the third clip a few posts. But when Davos questions him later about his reliance on blood magic Stannis gives zero fucks and defends it full stop. I say use what you got, everyone else does.