What a rank up gives in Guildrun
Heroes in Guildrun rank from C through B and A to S, and every rank raises the whole stat line. What changes is how much: the stat a hero's class scales with climbs two to four times faster than everything else, so the same rank is worth far more on the right hero.
A rank up is also what unlocks the rank up modifiers a class is offered, which arrive at rank A and again at rank S.
Ranking a hero up in Guildrun