It was because of elemental advantage. He slightly hurt Prometheus because his blue flames are stronger than regular flames.
Marco has overpowered and damaged Prometheus, with that, a Yonkous main weapon, then was smiling after it happened. Use any reason to justify it, it still happened.
Marco got damage in and received none. Didn't even need to use regeneration once.
Can you please show me the panels in Vista vs Mihawk where Mihawk was choking Vista with one hand?
Mihawk was hardly even paying attention to Vista, something u guys like to miss and now look where we are with the postponement coming full circle.
Can you show me where BM instructed Pero to attack Marco on her behalf?
I don't need to show u anything, the panels are out there. Big mom knew that Perospero will interfere and didn't even say a single word of him staying out of this fight.
She was okay with him attacking Marco which makes it a 2v1 which Marco had to look out for.