sorry for late response since you made it a discussion rather than a comment but ;

monster has 4 movesets, that can be changed by holding CTRL and pressing W or A or S or D
W is brawler, which is inferior to legend
A is maniac, which is the slowest
S is legend, which is arguably the best
S as legend for legion, which you need to enable in admin settings
D is hakumen, which is fast

each style works differently and has different mechanics, for hakumen SHIFT will be a parry, while for brawler and legend its a guard that negates damage, while for maniac its a way of attacking

the (heat) bar will only fill up if you TAKE damage, and you will lose heat for DEALING damage, the entire bar's mechanic is meant to be for counterplay
you can get more heat under special circumstances (like hakumen's parry or guarding attacks) but the main way to get it is to taunt with S+R

monster is strictly inspired from yakuza 0 / kiwami 1

question: how do grabs work?