So when 2017's Arkham Nights came up, part of the events included playing with "Ultimatums". And now I see a couple of new ones mentioned in the latest Return to Dunwich Legacy article.

Were these Ultimata provided as cards or are they written up somewhere akin to the Achievements in Return to The Night of the Zealot?

The Ultimatums from the Invocation event can be found on page 2 of this link: https://images-cdn.fantasyflightgames.com/filer_public/5b/f9/5bf9f287-9fa3-4274-8ad5-84c8b56ca93c/invocation_event_outline.pdf

15 minutes ago, Assussanni said:

The Ultimatums from the Invocation event can be found on page 2 of this link: https://images-cdn.fantasyflightgames.com/filer_public/5b/f9/5bf9f287-9fa3-4274-8ad5-84c8b56ca93c/invocation_event_outline.pdf

Thank you! Interesting, that the two Ultimatums listed as "new" on the Return to Dunwich Legacy article are also included in the link you posted. Perhaps because they will actually be printed for the RtTDL just like the achievements list was.