Idle Online Universe RPG

I was wondering how the upgrades in the "hunting" category worked in group.

In example, if I have hp reduction lvl 40 and my 2 party members have hp reduction lvl 25 and lvl 35, is the mob affected as if we had the skill lvl 100? (40+25+35) or just lvl 40? (which is the highest in the group). Same goes for time extend and treasure hunter.

I guess the question goes for the ascension upgrade "party gains" too.

Nope i think it is the person with the highest one

Correct, highest in party. It used to be the leader, but it just made more sense to keep it as the highest possible.

Regarding the ascension party gains skill, that only applies to you. Read it as "YOUR party gains", not "YOUR PARTY('s) gains".