2 Feb 2024
Once you've announced that you're casting a spell, players can't take actions until you've finished doing so. Notably, opponents can't try to remove cards from your graveyard to stop you from collecting evidence.
2 Feb 2024
Starting with the next opponent in turn order (or, if you cast Extract a Confession on an opponent's turn, starting with the opponent whose turn it is) and proceeding in turn order, each opponent chooses a creature they control to sacrifice. Then those creatures are sacrificed at the same time.
2 Feb 2024
If you can't exile enough cards to meet or exceed the required mana value, you can't choose to collect evidence at all.
2 Feb 2024
If evidence was collected and an opponent has multiple creatures tied for the greatest power, that player chooses which one to sacrifice.