MArcomage

What about these cards:

Mircamix
Fairy dragon
Black market
Avatar of vengeance
Flaming mirage
Succubus

Should these also qualify for revealing?

Micramix shuffles the hands, so both players don't know where anything is. No.
Fairy dragon puts them in known locations, so yes.
Black market, yes for both players.
Avatar of vengeance, yes.
Flaming mirage gives enough information aside from the played card position, but we're counting similar cards as a yes, so yes.
Succubus is a targeted copy, so yes.

I know I'm late to this discussion, but dragon egg should not be revealed, as doing so provides extra information. An opponent has no way to tell whether you have a second dragon in your hand, and summoning a dragon egg used to look the same as the dragon keyword not triggering in hidden mode.

Not so. The opponent has always been able to see whether the effect created a Dragon egg by looking at whether the gem production was doubled.

There are three cases that can happen when playing a dragon card:

1. Player has no other dragon cards in hand an plays a dragon card: No dragon egg is summoned and no gems x2 occurs
2. Player has another dragon card in hand and a dragon egg card in hand: No dragon egg is summoned and gems x2 occurs
3. Player has another dragon card in hand and no dragon egg card in hand: A dragon egg is summoned and no gems x2 occurs

Cases 1 and 3 used to be indistinguishable to your opponent in hidden mode. Now they are not.

While I'll concede that this is true at the end of that one turn, it's still easy to deduce, and really only valid the first time a Dragon is played. Following that, the opponent has enough information for subsequent plays of the keyword, barring a full hand discard. The alternative would be to have the Dragon egg be revealed afterward when the player plays the other Dragon card, or for the game to have to check to see whether other Dragons are already revealed, and that can get to be messy programming-wise.

For most plays, it should be obvious whether Dragon egg was drawn, and it's not worth programming special checks for the remaining 97% of the time.

Quincunx wrote:
I know I'm late to this discussion

Also, Rejuvenation is missing in the list.