Core vulnerabilities are more rewarding, but minor vulnerabilities are easier. I would try to break some minor vulnerabilities first when you're learning. You can try going for core vulnerabilities when you have some experience.
Is breaking vulnerabilities something you reliably do like every battles,
or even latter-on it's something that happens only ocasionnally?
before for now i even say if it's something easy to achieve or if it's normal that i have such a hard-time doing it.
Also what happens when you break a vulnerability?
what's the point and what does it influence?
All the opening levels get combined
okay thank you for the clarification, that's what i thought but i wasn't sure,
Now concerning creating openings, what would you say is the easiest most efficient to do so?
Because i can reliably make it when it's only a single-character,
but once 2 more shows-up i either have to choose to focus on a single character, or surround multiples at the same-time but then i don't have the time to raise any-stats
also most surround-phases i get last a single-turn,
i understand that the more openings have been made, the longer they stay surrounded.
but that means that i either have to choose to raise a circumstance stat-level for a single-turn,
or don't surround them to raise their opening-level but then they might get-away before.
Both preferably. I would advice you to try to find a chosen with minor vulnerability to Pleasure, surround them for a few turns (either with commander or by doing damage to their other circumstances) and then using caress first and then grind and pummel starting with whatever she's most vulnerable to. That'll probably let you surround her again for longer.
from what i understood, PAI and DIS are the easiest stats to create a lvl 2 opening,
the thing is that they also both seem to reduce PLE and INJ to a 1/2 multiplicator
how the hell am i supposed to raise both of theses stats on the first surround if i can only surround them by doing something that negatively impact what i'll do on the surrounding phase?