Fix second player advantage?
Low player offers bonus for going second, high player chooses play or bonus
Example bonuses:
Coin (colorless treasure)
0/1 wall
Food
Blood
Map
Incubate 1
Scry 1

Consolidate creature types
Eg: rogues = pirates
Soldier = knight
Siren = merfolk

Break color symmetry, add more split and hybrid cards.

Add learn cards, errata learn to be booster tutor