Collectible Card Game Headquarters

Describe the Bug:
Reproduce the bug as follows:
Play Underground Sea, Black Lotus, Mox Ruby.
Sacrifice Black Lotus to play Buried Alive. Put one Bogardan Hellkite and two other creatues into the graveyard. I tried various combinations for the other two cards (also only Bogardan Hellkite and no other creature), it didn't make a difference.
Play Exhume, put Bogardan Hellkite into play.
Deal one point of damage to the Birds of Paradise, the remaining four to the opponent. Order of damage dealing doesn't seem to matter.

Birds of Paradise come back into play.

Not sure whether this is an issue with Bogardan Hellkite or with the graveyard mechanics.

Which card behaved improperly?
Bogardan Hellkite

Which update are you using? (date, name)Which type? (duel, gauntlet, sealed deck)
Version 5-2020 10bda4ca0
Duel

What exactly should be the correct behavior/interaction?
Bird's of Paradise should remain in the graveyard.

Are any other cards possibly affected by this bug?
NA

If I remember correctly this was a result of having etb triggers work correctly when multiple cards entered the battlefield at the same time. This goes many years back but I think this is one of the cases that will only work correctly if triggers go on stack. Korath or Gargaroz will know for sure but not around unfortunately.

Fixed in 57846e8f1 ("Fix Exhume APNAP rules", 2020-05-22) at least for this case, and I think in accordance with game rules

I just separated the selection ( select_target_from_grave_source() ) from the reanimation ( validate_target_in_grave_source() / reanimate_permanent() ) into separate APNAP loops, both on resolution.

I just tested this and no creature comes back.

Ok that's interesting; for me it works on the posted savegame, but not on a new game. Coming back to it.

Bizarre - seems to work unless it targets the bottom card of the GY. Any idea at all what might be going on here?

We have met this in the past. I am not at home to test but I guess you will find how to solve this if you check how Korath dealt with this here:
viewtopic.php?f=110&t=17520&p=189352&hilit=doesn%27t+fetch+bottom+card#p189345

drool66 wrote:Bizarre - seems to work unless it targets the bottom card of the GY. Any idea at all what might be going on here?

Fwiiw: I can confirm this. When I killed two creatures with Bogardan the first remained in the graveyard but the second came back.

Oh I get it - if it's targeting the bottom card, select_target_from_grave_source and validate_target_from_grave_source return the position, which is 0 for the bottom card; therefore using them as the conditional is a break for that position. That's why he converted them to booleans checking outcome > -1. Thanks, Aswan!
Fixed! 1cf5bb408 ("Exhume switch to boolean", 2020-05-25)

Wow! That sounds like you gained some deeper insights beyond this bug .