It is all minions that don't start in your deck, including discoveries or other random generators like prince malchezaar in wild. Stonehill defender would be a nice place to start for example. I think the standard thoughtsteal isn't going to do it.
But that's the problem that lady in white had. Good cards with a lot of cards, but most of them suck, if you don't draw her. I think this takes way to much effort just for a tempo boost. Cloning priest is stronger
I've been trying to make Princess Talanji work for most of yesterday. I tried tempo, control, dragon, and quest priest.
The card itself is fine, generally delivers some good tempo. The bigger issue is trying to 'steal' minions from opponent decks. I had multiple matchups where the cards I stole (pirates, beasts, 'hero-power' buffers) were super-synergistic for my opponents, but were dead cards to me.
At this point, the card may end up as an addition in some priest archetypes, but it's not a build-around card.
Maybe this is what you're looking for? It has some stealing going on but mainly relies on playing and generating a bunch of weaponized pinatas which allows for some pretty awesome Talanji action. Twice now I've gotten Zentimo and I was able to cast Seance on Talanji and a bunch of other legendaries thanks to him, which immediately sets up another good Talanji play.
But that's the problem that lady in white had. Good cards with a lot of cards, but most of them suck, if you don't draw her. I think this takes way to much effort just for a tempo boost. Cloning priest is stronger
Occasionally gives helpful advice.
Maybe this is what you're looking for? It has some stealing going on but mainly relies on playing and generating a bunch of weaponized pinatas which allows for some pretty awesome Talanji action. Twice now I've gotten Zentimo and I was able to cast Seance on Talanji and a bunch of other legendaries thanks to him, which immediately sets up another good Talanji play.