Hi, haven't run SoM before but saw in a run that there's tricks involved for magic%, could someone explain them and how they work/whether they can go wrong?

Hi,
there are 2 important things to know for the trick with the canon guy,
1) Before using the barrel on yourself, wait until you see the name "Barrel" on the top left as you open the menu. If you open the menu and spam the B button to use the item as fast as possible, you will be too fast and the glitched menu will be a different one if step 2 works. After using the item, you need to talk to the canon guy exactly 9 frames after the "Barreled!" textbox disappears.
2) If step 1 successful, you'll enter a glitched menu in which you need to do the following inputs:
Left x1, B x1, Left x1, B x1, Left x1, B x1, Left x1, B x1, Left x26, B x1
The first 4 left inputs have a small delay (the canon guy will freeze for a short moment) before you can press B, same for the first 2 left inputs of the last 26. The last 24 left inputs can be mashed as fast as possible.

Good luck!