Powering up

Ok on my seasonal character im paragon 397 and I got about 503k powering 11mil in toughness and about 600k in recovery. I have the set for the necromancer that you get for beating the 1-4 chapters. I can do gr 50 but now im stuck i get one shoted to many times on 55 and up and ive hit a wall i don't know exactly how to get stronger ive followed a build for my character but like the rings and amulet when I find for the build its asking for they all lower my.power and everything even when I use the cub. I don't really understand how to get stronger past the point im at any near gear I get just lowers my power or GREATLY lowers my toughness and recovery just for alittle boost in power and im talking 1 to 10 percent and ive tried watching YouTube and I just don't understand what to do i want to atleast get to gr70 and I have a few ancient gear but they also lower my stats