Disclaimer: This is mostly educated guesses based on names and what happened when the book was opened. If any of these have actually procced, I haven't seen it yet.
- Rogue umpire is the classic incenarations.
- Knight umpire is the one who sends players on quests to the shadows. Seems to act like the Foreshadow Will.
- Mage umpire is probably the one handing out curses.
- Bard umpire would then be left with alternation. I saw someone speculating it's a riff on alternative music.