not for mobileOHK Sniper rifle is terrible, and the best PVPers know that. It's bullet is small and easily avoidable. If you watch somebody like Shinden or SashEx play, they don't stop moving and rarely get hit. Ninshu has also showed long list of deaths from somebody trying to use an OHK sniper, and failing horribly. Nebula Blaze can run out of mana fairly quickly, and terrarian has very limited ranged. With more skilled PVPers, you won't ever see them, you only see their projectiles at most. And, as mentioned before, you'll never see a skilled PvPer, so the Rainbow Crystal is useless. They are good in PvE, with the excepion of the sniper rifle.