Birth of the Blades is the twenty first episode of ThunderCats (2011 TV series).
A flashback shows when Mumm-Ra first had the Sword of Plun-Darr forged, having to destroy a star to do so, and killing billions of intelligent people in the process.
- Pumyra finally disregards her grudge against Lion-O after he saves her life numerous times.
- Although they appear in this episode, neither Cheetara nor Tygra have any lines.
- Kaynar: Ah-ah-ah. That sword doesn't belong to you.
Lion-O: Maybe not. (draws the Sword of Omens) But this one does!
- Mumm-Ra: Your ancestor thought he could beat me as well, I'm still here, where is he?
Lion-O: You're looking at him!