There is an attack speed cap inthe game engine, you can change it but that's not my point.
Rune Golem starts out with a powerful but slow attack. His modifiers can increse it with attack speed modifier, but that's capped at 80%. But I want maybe 100% or 120% because he is so slow to start.
So at max they have doubled their BASE attack speed (if they get their charge that high). Then OTHER Modifiers increase it with a cap of +80% to THAT speed.
You are absolutely correct. But being like trick-suggestion for modders, there is good idea to know HOW attack speed is calculated. Also it is good to know WHAT is mean 100%. So I'm adding addition to this post (this information i'm already published somewhere on this forum before):
So text below is kind of warning for modders. USE this if you understand what you do. If you can't spent 0.1-8 hours to reproduce text below - just never touch this numbers. NEVER. Otherwise you will get something what works somehow and you as modder then say "ah, this fucking TQAE engine so buggy, so they are shitty why they are even touch it, suckies and sucks my socks! (c)". No. There is not a modding way. You pick real number which has NO UNIT of measurement. It has some effect. This effects are complex.
Reversing logic below tooks for me about 4-8 hours in practice and analyzing real database full of real items. And i'm still not sure what this is calculated right (because magic numbers still here).
What mean 100% attack speed? I'm already wrote somewhere on this forum... There is exactly not 1 attack per second. Much, much faster. For PC 2 APS is 126.6% (on Normal game speed for sure). Incrementing BAS is like total speed for everything. And points of speed they are in unkown scale (three is some real number which relative... to... animation which rarely adjusted or understand (most of time)). E.g. which vanilla PC's BAS? 0.74. Why it ever 0.74? Why vanilla knife have 0.5? I mean what without having this details it is hard to predict this numbers and more over - game have no interface to understand what you finally got especially for pet or monster. (Surely, they fine testable visually, but visual testing can't distinguish actual nuisances... and they are pretty important).
And there is really dark area.
For usual weapons formula is next:
63.3f * (1 + baseAttackSpeed / 0.74f);
Where 63.3 - magic constant. For throwing weapons it is 57.0, for staff - it is 65.0. (Real numbers are bit more "strong" like 63.333336 or 65.3125031 or 57.0000006

). Again, why this differences? I'm did not know. I'm doesn't see any real difference in animations, number of frames or setup. I'm feel there is just sucky constants inside of game engine. (And yes, 63.3% is 1 attack per second). Whoa?
baseAttackSpeed - is weapon's BAS. 0.74f - it is character's base attack speed. So, now you you can calculate PC attack speed (0.5 is knife):
63.3 * (1 + 0.5 / 0.74) = 106%
Let's increacse character's BAS to 0.84. Will be now our PC do job faster?
63.3 * (1 + 0.5 / 0.84) = 101%
Ah? Oh-oh. It starts to do work slower by 5% be we up his BAS by 0.1. I'm think there is good and simple explaining what I mean.
Shield is way more special - normal shield's BAS which did not affect your's attack speed - is... ZERO. Yes. Shield's attack speed is additively stacked with weapon attack speed if i'm remember correctly. So, if you want create shield with -10% to attack speed without char speed modifier - you should put some negative number in BAS (and -10% will be relative to PC, but for monster same shield might work as -20%, again back to equation above!).
I'm just show a warning, ruling this numbers it is absolutely legal, correct and valid way to rule your mod. Do things which you want to do. But everytime you touch them, you should keep in mind, what there is non-linear dependency driven by equation above. In practice this means, what small adjustments, like
@Bumbleguppy use - can be treated as linear and can did not care about actual equations. But higher-level adjustments will not be scaled linearly, and there is good to know how this works.
PS: And finally you can see how it is conflict with message above when text says to add number to add additional speed, while it will made monster only slower.
@Bumbleguppy - this is easy to field test. Add more massive number and differences will be seen. Still might depends on what is added. I'm strictly speaked about `characterAttackSpeed`.