King of the Hill is related to annex somewhat. You have to enter the ring that will spawn near a weapon on the map. The point it is at is random. But unlike annex, the location does not change during the round. It will be at the same spot no matter if you get all 120 points out of it at once, or in several tries.
Once you capture the ring for your team, someone on your team MUST stay in the ring, or else it will revert back to neutral. Also, while your team is in possession of the ring, your team-mates will not respawn until you lose possession, giving King of the Hill a big distinction from Annex.