Krivis doesn’t have much support left, only Melstis and Zalciai, and Zalciai can be compensated for cheaply now by crafting scrolls. Yes, with the attribute boost and a skill gem it’s still decent for others who don’t have any crit damage boosts, but since meta is heavily relying on Ataka + crit boost in PVE, that’s probably not a reliable boost for most meta parties.
Krivis is still nice for a damage class,though, because it has decent magic damage over time.
Since most solo content is just beating bosses, every Crusader build more or less can solo, because of the high SFR% and the low skill point disparity of the class. In the end it’s more about min-maxing than relying on certain builds to breeze through content. Having fun is very important for this game, because it offers little engagement otherwise, so don’t be discouraged if your build does not carry you as good as another build option.
Clerics cannot use staffs, they can only use rods.