From Halopedia, the Halo wiki
Broseidon is a multiplayer medal available in Halo: Reach. It is earned by spawning in a teammate fifteen times without dying in. It is represented by a purple spawning icon on top of a silver six-pointed star.
- The medal is likely a reference to the third panel of this videogame-based comic, which gave the pre-existing slang term "Broseidon" a resurgence in popularity while Reach was in development.
- Broseidon itself is a combination of the words "bro"(-ther, i.e., buddy) and Poseidon, the Greek god of the sea.