Question on Wylls Imp: When did they make it so you can't separate him from the group, or has it always been like that?
It’s always been like that. If you want Wyll’s imp to stay put while you control other characters, you need to put it in hiding mode (even if it’s already invisible). Beware, though, as this technique may leave it stranded halfway accross the map without you realizing.
Even as one of the few Wyll advocates on the forum, I have to admit the imp’s usability has been a pain point.
