Warning: Full spoilers for the episode below. "Revenge" may have not gotten around to the actual revenge part of the story until the final ten minutes (Vikings episodes tend to work that way, structurally), but most every part of it was still filled with really intriguing and sinister things. Firstly, the culture of the Norsemen fell into fierce focus again with Lagertha holding a blood sacrifice -- human blood, that is -- to bless the massive army before they invaded England.