

I got the achievement for Aurora in that battle then I switched to have the card target Fugoro instead and repeated the method for him. The boss battle of Chapter 2 was the most productive since bosses have lots of health I was able to just block (more or less) for quite a few turns in a row before having to mulligan the fight by quitting to the main menu then repeat etc.

I decided to try to prolong each battle as long as I could to keep seeing more cards every turn, mostly just trying to block to prolong the fight as long as possible.

I used an Aurora card called Spellwhirl (uncommon) that I picked up in Chapter 2 and I also went into a gem mine in Chapter 2 and picked up a gemstone called Phasestone (epic.) Spellwhirl let's you choose a hero and it generates 2 random cards from that hero's card pool into your hand and Phasestone puts Spellwhirl on top of your deck at the end of your turn so you can keep drawing it every single turn. Epilogue 0 and both heros were at about 90-92% in the achievement tracker so 4-5 more cards needed for each. I got this in an Aurora + Fugoro run and got the achievement for him as well.
