You are going to Watch Avengers Assemble Episode 21 online free episodes with HQ / high quality. Stream cartoons Avengers Assemble Episode 21 Online By the Numbers. The Avengers and the Cabal have a huge confrontation that leaves the team forever changed. Tony also learns that “the stats” can’t be trusted every time as there’s no substitute for human intuition. This even proves a point to Iron Man when the Avengers and the Cabal target the Tesseract.