The source for them using CLIPS is a conversation I had with Arena team lead Ian Adams in a Magic-community Discord.
The source for the bug is a video WotC did that I can't find right now that featured the Arena team talking about developing Kaldheim - the bug came from the card Alrund, God of the Cosmos.
The source for the bug is a video WotC did that I can't find right now that featured the Arena team talking about developing Kaldheim - the bug came from the card Alrund, God of the Cosmos.