As it turns out the player was using marchesa's "all players have dethrone" ability in combination with molten primordial to permanently steal the creatures. Is able to do that? In other words he gained control of the creatures, attacked the player with the highest life total, and then when the creature's died with the +1/1 counters he brought them back under his control.
Assuming the stolen creature actually died with the +1/+1 counter on them (Zealous Conscripts and Molten Primordial do not do that on their own, but a Marchesa player might run free sacrifice outlets such as Phyrexian Altar), yes. When the creature changes zones (battlefield to the graveyard, and then later graveyard to battlefield), it becomes a new object with no memory of its previous existence. While the Threaten effect has a duration that ends in his cleanup step, the creature that was stolen no longer exists; instead, a new object that just happens to have all of the same characteristics as the stolen creature enters the battlefield at the beginning of his end step.
Zealous Conscripts Molten Primordial
Warning issued for failure to use card tags.
- Teia
Two Score, Minus Two or: A Stargate Tail
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