The map pool for both modes got updated and is the following:
Duel
- Blood Covenant
- Blood Run
- Corrupted Keep
- Ruins of Sarnath
Sacrifice
- Blood Covenant
- Ruins of Sarnath
- Burial Chamber
- Lockbox
When it comes to Sacrifice, it is a one champion limit and you will not be able to change the champion during the match. As confirmed by id Software, all players who qualify to Quake World Championship and the regional LAN finals for Sacrifice will have their flight and hotel paid.
Note that change in ruleset is still possible and ESL didn't make official announcement yet.
Links: Duel Ruleset, Sacrifice Ruleset