My biggest take away was its important to take out the Black King's high priority minions while making sure you are getting a healthy dose of face damage in each turn via Rook or Queen, otherwise you will just keep going into fatigue due to his cheat.
How does one take out his minions while also hitting his face with your highest damage pieces??
Its been a long time! Sorry if its worded oddly, I meant to trade with your other pieces will getting face damage in with Rook/Queen exclusively. I will say that this fight's RNG can be very frustrating--maybe try a different one out and come back to it.
Ended up doing it with the strategy of playing 1 on turn 2 and 3 on 3 for board advantage. Can't stress enough how you just need luck to ensure he doesn't draw answers to your board state. There is also so much misplay that can occur.
Went back into the adventure and saw I only needed heroic Free Medivh and Heroic Chess. I beat this chess in two attempts by following the mulligan and positioning tips from Taiji. My first attempt was a 1/6 on 1 and 2x 1/6 on two and was cruising from there. The reason I lost was that my bishops were both on the bottom, so I wasn't able to generate value by keeping rooks and knights alive. I got him to 7hp, but just ran out of steam. Second attempt had same start but got a bishop much earlier which kept me ahead the whole game while doing 2-3 damage a turn to his face.