What happens if a quest card asks you to search the encounter deck or discard pile to put into play a unique enemy (that you need to kill to resolve the quest) and that enemy is in the victory display?

Ungoliant's Spawn, I presume? I can't think of any other enemies that *should* be unique but aren't... so cards like None Return can't interact with them. That spider, though...

I think you're outta luck.

I think you are doomed.

I would just house rule it to allow you to search the Victory display as well.