how much RR is too much RR?
Depends on many factors, but usually the more the better. But you can not have too low +%dmg or crit chance/dmg either.
So long as you’re not compromising any other important parts in a build, more is always better. You can’t apply RR to kill stuff if you can’t keep yourself alive to begin with 
is there any sett for vires might fire build? my first time playing the game so no idea of the setts that exist for oathkeeper/inquisitor
Yup, Vanquisher https://www.grimtools.com/db/itemsets/142
Here is a beginner friendly guide I made for Vires Might build ☄ Collection of malawiglenn's Beginner Friendly builds
is RR allways good even when i got - 120% fire resistance? when does +dmg become better then RR?
Depends on the monster’s initial resistance and your initial value of +%damage.
If a monster has 100% resist and i have minus 200% resist does that mean my attack will now do double dmg?
yes compared to if the monster had 0% res.
from 100% to -100% you deal infinite more damage since with 100% res the monster is immune
so i hit a boss with 0% resist for 100 dmg then i add more reduce resist gear so the boss now has minus -100% resist i will now hit the boss for 200 dmg?
this seem a bit op
That is how resistance reductions works yes.
For physical damge the situation is different, then you need to plow through armor first.
is there an updated list for this new expansion on which types of RR stack? devotion items talents etc etc
Things have not changed…
Wow look what I found, one of the first posts in the guides section 
🤯 malawiglenn’s guide on game mechanics for beginners xD
i used google to search and links are broken there rip
Links are broken because the old forum no longer exists, it vanished into the void. Do a search here for a thread title or use keywords to find what you’re looking for.
if my skill hit for 50% weapon will Ignaffar’s combustion https://www.grimtools.com/db/items/8227 procc reduce the resist by 5% instead of 10%?
No, it will apply the full 10% regardless of which skill procced it. RR and weapon damage interaction only happens when it’s the weapon damage itself applying the RR. If the RR is on the debuff itself, the weapon damage doesn’t matter.
nice this makes hitting 100% RR easier