Now that I'm busy writing book 2, I decided to sit down and make a teaser for it. It touches on the key new aspects of the game; kingdom management, allies, your army, and the need to become truly the Winter King. MC's days of being a deadbeat student in Edinburgh are coming to an end.
Deadbeat student... yeah he did not graduate but there is still that renowned university in Lagos he can get his diploma from on account of his life experiences
Joking aside, have you thought about revamping MC stats and the combat system?
Don't get me wrong, I love the cards game combat but our MC has matured to god status and it did not reflect much (only Power 2) on his card game abilities or his health stats.
He's got a 3 billion gallons mana pool and a soul-sucking sword that is completely useless (outside of the "narrative combat").
He can still be pawned by a defiler if you play drunk.
Our MC god definitely needs some beefing up.
For all of the key conflict moments (boss fights), you used Deux ex Machina solution - dropping out of a card combat game and resorting to the narrative.
It works fine but it's not an ideal solution in the long run.