Neverending Artifact farming. And even if you do roll one with crit rate and crit damage, expect your upgrade gacha to put it all in the useless stat that is often flat def or flat HP.
I farmed a decent 3-stat Tsuba. Atk% main stat, ER and Crit% followed with HP%. Rolled them all at HP% and Def%. Pain for future Baal, yay for my C6 Noelle.