I was playing as Sire Denathruis with the Cosmic Duality anomaly, which I chose Master Nguyen’s hero power.
My quest reward was “At the start of your turn Discover a Buddy”.
I was choosing the buddies just fine, but it wouldn’t give me any options for my other hero power, or if it did, it was ONLY “Discover an undead, swaps after each turn” (Rat Kings hero power).
Played as Gruff, and took as second hero power “Upbeat Harmony”, so I managed to get a triple reward and wanted to get a copy of it, I got one but it said “Discover a minion from Tier 0.” 
Here is a screenshot [Screenshot](h t t p s://ibb.co/84bnc0DR)
Same today with Marin, only get rat king ‘elemental’ every other turn.