calcualte monster damage on me?

Regarding Paracelsus's point, I just experimented a bit and found that plugging the monster's attack into the magic formula as MATK, with monster level as base spell and 100% mastery, almost works. I say almost because it breaks on certain extreme cases, such as squid ink, level 200 monsters, electrophants, etc.

I'm pretty sure that monster attack is the sole factor in its damage output, disregarding the defense side of things.

Squid ink is considered a magic attack, not a physical attack. That might be a little different. We're just talking physical damage here.