and here's an example of a skill tree
the round s-circles are for s-rank memories, which means their effects are only enabled if you put a s-rank memory into those
to get s-rank memories you either have to be lucky or farm them. idk what to compare it to other than tact's free character/monster farming. but instead of only having to max out 1 monster, you have to max out 8 of those for one vocation on a character. each vocation is a different color, so you can't just use the same 8 over and over again