Just to be clear: Every time you cause intrigue, you make your opponents' Mystery stronger?

Also you really need to uncover a Mystery only once and unless someone makes an active countermove, you get access to intrigued cards indefinitely?

Both of these seem weird design choices. I could see Mystery being a token with "Sacrifice this Mystery: You may play a card you have exiled with intrigue."

Heck, going with the intermittent token is something I only keep in, because you seem to already mechanically care about the token.

I think, a manifest variant could be neat:

• Cause intrigue. (Put the top card of an opponent's library onto the battlefield face-down as a Mystery enchantment. It has ", Exile this Mystery: You may play it this turn.")

Yes. If an opponent has at least one Mystery token, that player can cast your exiled cards.

The parasitism of Mystery tokens and Intrigue were something I grappled with. As permanents, Mystery tokens can have cards that care about them .

Intrigue is a bit harder. I will say that I do want cards to be in exile until they are played and I did want it to be a mechanic that affected all players. I think I created Mystery tokens to so that I had a way to balance casting permanents out of exile (although all costs still need to be paid).