The Lich King: Lich King will acquire multiple Frostmournes if his hand is full on turn 7

[Jetz72]

This is was shown in the process of issue #994:

Log of the full game: https://gist.github.com/PattuX/8b4d5b8fd2704ca61f9c3d01393df7ea Replay: https://hsreplay.net/replay/8JsRaFxe9Q9UCG8Bd6498m First Frostmourne: T7, second one: played T8 and destroyed T11

The fact that he managed to even get a second Frostmourne is an issue in its own right. If his hand is full on turn 7, the trigger to create the sword on top of the deck (EffectIndex=6 in the logs) will instead transform the rightmost card in his hand into the weapon. But unlike the typical case, the trigger evidently does not expire when this fallback happens. Whatever the reason, it runs again during the next turn, giving him a second Frostmourne. This is almost certainly unintended.

[Jetz72]

Still happens: https://youtube.com/watch?v=pM7jVlBZHTM&t=2m28s

Also demonstrates that it's a random card, not necessarily the rightmost one as said above.

[troggnostupidhs]

Deck AAEBAaCsAwSdDYgUhrECmu4CDZ8D5QT4B/IM+Q6StALwuwLSwQLz0wLl9wLqjAOClAOznwMA

The leftmost card (my perspective) was changed into a Frostmourne.

And it was a middle card when I later copied his hand with Azalina.