Collectible Card Game Headquarters

Describe the Bug:
If I use Green Sun's Zenith to search for a creature to put on the battlefield selecting x = 6 (e.g) and use it on (Savageborn Hydra at least probably all creatures with x in their cost) Savageborn Hydra enters the battlefield with 6 x (+1/+1) counters on it.So as much you pay for x for Green Sun's Zenith that much x the creature gains.

Which card did behave improperly ?
?

Which update are you using?(date,name)Which type(Duel,Gauntlet,Sealed Deck)
2014/02/18: Born of the Gods v2 - DUEL

What exactly should be the correct behavior/interaction ?
Creatures with x casting cost are put on the battlefield with 0 x +1/+1 counters on them when you use Green Sun's Zenith.

Are any other cards possibly affected by this bug ?
-

Also tested with Primordial Hydra, so it isn't card specific.

The same bug have - tested:
1- Chord of Calling
2- Wargate

Untested cards that have same ability:
3- Lin Sivvi, Defiant Hero
4- Reshape
5- Taj-Nar Swordsmith
6- Tezzeret the Seeker
7- Transmute Artifact?

One more bug I have noticed with Green Sun's Zenith is that I saw AI using it about 15 times and NONE it picked a creature to put on the battlefield.

All fixed.

Your fix breaks Spell Blast, Spell Burst, and anything else that inspects the CMC of a spell on the stack. The right way to do it is to check whether the X-cost creature spell was played for free; an easier hack that might work would be to clear x_value at the start of Green Sun Zenith's resolution, or possibly put_into_play().

I see, however Spell Blast needs recoding (interaction with Summoner's Trap), and Spell Burst doesn't look at the X value at all (and this is obviously wrong).
I was thinking to add a check on "get_cmc" for SF2_X_SPELL and then a check for "info_slot", as almost all the cards that have "X" use this method. It seems to me a more precise way instead of checking a floating variable, which will be completely inaccurate if we can ever implement a stack system more similar to the actual one.
Obviously, older cards will need to be recoded.

Special flags aren't, in general, usable on non-permanents; too many of them use their targets as actual targets, and X spells are the most likely to do so. Plus, now you're adding info slot to their CMC no matter where they are, instead of just on the stack, and whether or not you know they're storing X there.

I agree, but speaking of X spells, I bet you'll rarely see spells that targets more than 10 different targets at once, so I think we're still in the "safe zone" speaking of Special Flags.

These all seem to be fixed,I don't know if Lin Sivvi, Defiant Hero is as I couldn't find a rebel permanent with X casting cost to test it.

However the interaction with Spell Blast still is broken?
Spell Burst seems to work fine with X spells to my limited tests.

No, Spell Blast was recoded and should be fine now.