Actually most of the time, there’s just two. Game guide mentions that monsters normally don’t have any offensive stats except for 5% crit and then there’s % resistance penetration from area level the monster spawned in.
Some monsters - for example Pontifex Aurelus that was in the linked video - have additional stats which are also listed on the tunklabs site, in this case it’s 474% more damage.
So the formula for his damage should be Meteor base damage * (1+4.74) where Meteor is the monster version, not the player version. Then you apply player defenses, and reduce player Resistances by applying the Penetration from area level.