Joraal was imprisoned by a noble house in Demacia, so I'd like to think they used their political connections to trap him with petricite. I'm not hiding the fact that the new Darkin in LoR are among some of my favorite additions of all time.
Since Taarosh was imprisoned on the Blessed Isles, it seems probable that his halberd was keptin the vaults of Helia. So I'd like to think Thresh tortured him during that time, since an older iteration of his bio noted he liked tormenting the living artifacts.
Since Sun Creature posted the full credits for Return to Valoran City teaser, looked a few of the artists and saw some other concepts like Xayah and Rakan's lock by Anh Tung
Nilah - Q AD ratio reduced from 90% - 130% to 90% - 120%- Q crit amplifier increased from 100% crit chance to 120% crit chance- Q healing increased from 15% crit chance to 20% crit chance
Aron Elekes actually wanted to go even more abstract with Mihira's design, but decided to give her some more human features because she ultimately still had to be relatable