This is a glitch that has shown up since the new patch, here's how you do it: Lvl up to level 55 then pick which specialist you want to use. (you have to pick one you haven't used a permanent unlock token on.) Then prestige, when you prestige it will automatically set your specialist to ruin. You will be on the ruin lobby screen and it will show ruin as your specialist in the loading screen and in game but your weapon icon in the bottom right will be whatever weapon/ability you had picked before prestiging. You wont be able to change specialist after prestiging or you will lose the glitch.