This question came up specifically in regards to Rhaegal: Reaction: After you win a challenge in which a single Stormborn character you control is participating, choose and stand a Stormborn character. (Limit once per phase.)

Now, does a challenge phase encompass all player's challenges, or does each player begin a new phase. In the rulebook, it looks like the challenges phase is all one phase, each player acting when they are the active player. But then, Rhaegal's limit of once per phase may as well be the less confusing once per turn (since challenges are only issued during the challenges phase.) This wasn't a long debate - we went with what seemed the rules, and treated the challenges phase as all one block, but I wanted to check and see if we got it right.

Thanks for any help.

There is a single challenge phase in which players take turns being the active player. So "once per phase" encompasses everyone's challenges.

Rhaegal's ability wouldn't work as "once per turn" because "turn" isn't defined for this game. So would that mean "round" or "player's turn as active player"? There is also a benefit to the ability being "once per phase" in that some future effect may create extra challenge phases in a round, or allow challenges to be initiated in other phases (both effects existed in earlier versions of the game).

Yup, you got it. Note that in 1st edition there were abilities that allowed you to initiate challenges in other phases. If those were to make a comeback, the 1/phase limit would be very different from 1/round.

ktom and Istaril are right.

Recarding Rhaegal and his text on cardgamedb. The text has the word "single" which does not appear on the card. Is that intentional? I was asking myself the question how this would be different from

The Knight of Flowers

While The Knight of Flowers is attacking alone, ...

The big difference would be that Rhaegal winds up not being self-referential, and working on defense as well as attack.

The "single" qualifier is really weird, since there is only one Stormborn character and, for thematic reasons, it's very unlikely that there will ever be another one not named Daenerys Targaryen.

Unless they introduce trait manipulation effects that would allow players to simply give the trait to some character, thematic or not.

Well, FFG got a little carried away with this in 1st edition. Hopefully, they won't allow arbitrary trait manipulation in 2nd edition (it was fun to give out silly traits - the limitation that you could only give traits that were printed on some card wasn't much of one - but it was too much at times). Still, it's a weird error to make (assuming the people entering the card data on cardgamedb are not privy to future cards).

Maybe FFG know something only they and GRRM know about new characters

That could explain the card text containing "single". But it doesn't, it's been added by the folks who entered the data in CGDB (which is owned by FFG, but that doesn't mean data entry and card design are done by the same folks).