Which DLC do you need to host "Sudden Death"? (HD, Steam)

Mode I enjoy the most, but very rare, so I want to start my own.

However, the option for sudden death doesn't show for me when choosing a mode.
Regicide, Relicts and all the others are there, but no sudden death, even after picking extension as option for the game I want to host.

Do I need another DLC for this? I only got one so far.
I'd love if you could help me out, low pop sudden death games are the best real diplomacy games for noobs like me <3

any idea? thx