Oscar Isaac gives his best performance so far depicting the dichotomous Marc/Steven. He illustrates their differences sublimely, in voice & vocabulary, facial expression and body language, viscerally incarnating these two disparate men struggling to share a body.
The first half crawls along, but is effective tension building. Night and tomb scenes are too dark and the effects budget was blown on last week's spectacular moon-magic, but these are minor quibbles.
Innumerable self-referential Easter eggs and nods to both Tomb Raider and Inception, round this out to the finest episode so far.