As to the poll, I think Bam's new ability is Both a time manipulation and an advanced copy of Aria's ability. Since the Blood spilt from Aria reversed its flow and returned to her, the main component o it has to be a localized time flow power, it should only affect what Bam directs it at.
If the above is true, then we might see a situation where Bam attacks white by decomposing him of his souls, and reverting him into soul-less hence powerless version of his adult self. The effects could then be interesting. A fitting ending for white could be an aged version of himself if he had not gained the souls spell, and since his climb up the Tower was soul spell based, and not Shinsoo based, I can see him turning into a pathetic haggard old beggar, the opposite of "His Majesty".
The only question then is whether Bam would directly kill him, if he does that would fulfill the Dark Turn that SIU hinted.