So lets say you have Codex of Ages out with the Elder Sign sealed on it..then you draw Serpents of Yig.

Are you able to use Codex's ability? or the token immediately gets sealed on Serpents, as soon as the Codex gets discarded, so it is not in the bag in the first place?

The section of rulebook on seal explains this clearly.

eg. you only seal out of the chaos bag and the effect fails otherwise.

Yes, I am not sure you can play a card that has conflicting seals though. Not sure if this is 100% correct, but this is how I remember it.

Let me just post this although its better formatted in the pdf:

Yeah. If you have Codex in your hand and know, through Scrying or other effect, that the Serpents is next your next draw, you can play Codex to prevent the Serpents from being able to seal the token when it is drawn. Then, when Serpents of Yig is drawn, as part of its entry to the table, its revelation text resolves. You search the bag, cannot find the token, and then put Serpents of Yig into your threat area.

As some future happening, the Codex of Ages leaves your play area. The token is then returned to the bag. The Serpents of Yig cannot then search the bag for the token, because it that effect was a revelation effect - which can only be triggered (and must be triggered) when the card is drawn.

41 minutes ago, Jobu said:

If the specified token is not in the chaos bag, the card cannot enter play.

I'm actually pretty sure that whichever of these hits the table first, the other cannot be played and either remains in your hand in the case of the asset, or is discarded in the case of the Serpents.

The Serpents don't have the "Seal" keyword; they seal the token as part of their Revelation effect. As such, they can enter play regardless of the chaos bag's contents, though their Revelation effect can still whiff.

7 minutes ago, Soakman said:

I'm actually pretty sure that whichever of these hits the table first, the other cannot be played and either remains in your hand in the case of the asset, or is discarded in the case of the Serpents.

I would be shocked if this doesn't get ruled to be for Player cards only. I would suspect the intent is the Serpent enters play just fine, but doesn't seal anything.

Just now, rsdockery said:

The Serpents don't have the "Seal" keyword; they seal the token as part of their Revelation effect. As such, they can enter play regardless of the chaos bag's contents, though their Revelation effect can still whiff.

Not true, though I had thought that as well. The wording states that cards that seal, either with or without the seal keyword, have the same effect:

Hmmm... I get it, but that's a weird distinction. Now I feel as if this is another of those rules I'm going to always apply incorrectly. Good to know though.

I think the difference is that the keyword makes the sealing cost. Since the Codex's Seal keyword is a cost, if it can't be paid, the card can't be played.

The Serpents sealing is just an effect. The card can come into play, but the effect fizzles.

EDIT: Somehow I skipped many messages, this is already resolved... oops.

This is in agreement with what is in the FFG Starter Decklists document: "if the [elder sign] token is sealed on Serpents of Yig, you cannot play The Codex of Ages, and if the [elder sign] token is sealed on The Codex of Ages, the Serpents of Yig cannot seal it."

Kind of interesting that his signature asset actually counters his weakness a little bit - usually it's the other way around.

Edit: Although I guess it's not unique... Daisy's does the same, and there are probably others I'm not bothering to think of.