ShadowDark Monster To Hit Math

It’s a personal thing. I like it when monster math is simplified to make it easier on the GM. Monsters with strength scores just muddy the water and force you into a derivative cycle of math to figure out basic bonuses.

I get why people want monsters to follow the same rules as characters, it makes for a mechanically consistent world. However, this is only for the GM. Characters never interact with that math or see the statblocks. What is the Ogre’s strength score? I wouldn’t give out more than “a lot”.

Like I said, it's personal.

Thus I did what all good nerds do: I wrote down all the attack bonuses and hit dice of the monsters in the Shadowdark bestiary, took the averages, and smoothed it out to get an equation. It’s pretty easy.

Average attack bonus: For creatures under 10 hit dice, +0.75 attack bonus per hit dice, always round any decimal up.

Advanced attack bonus math. 

Creatures have a -2 or +2 variance to the attack bonus equation, but there isn’t a hard and fast rule to determine when to apply it. My best guess is to look at humans. The attack bonus of human enemies with combat training (knight, assassin, soldier, etc.) in ShadowDark is exactly the average attack bonus calculation above. If this creature is more dangerous than a comparably trained human, give them a boost. 

Compatible math

The basic Shadowdark equation shows broad compatibility with OSR bestiaries. You could use the attack tables in OSE, and for anything under 10 HD, be within 1 of the standard Shadowdark equation. Are players going to notice a 5% difference? Probably not. In short, for creatures under 10 HD you can pick from the following options:

Easy: Use OSE attack tables, or even the standard +1 per HD if you want. It doesn’t matter.

Slightly Less easy but more accurate: +0.75 attack bonus per hit dice, always round any decimal up. Adjust from -2 to +2 based on the creature's ability to clobber a similarly situated combat-trained human.