Fable of the Mirror-Breaker is everywhere, and most matchups have at least a couple important artifacts or enchantments to get off the board
The only concern I have is that since this mode seems so much more equitable to the player what will it ultimately do to the physical hobby
If you insist on keeping it around, look for more cards that produce Map tokens, and find room for Path of Discovery in your deck
It can give your combo deck early plays of value and later on add 2 critical mana
The formula for the Critical Point is (solving for D): D = (53*4 - P*7/8*11/12 - R)/(N+W*7/8*11/12) Constants: 7/8 is an adjustment for non-Rares (ie, Mythics) in the reward packs, 11/12 is an adjustment for getting Rare (1/24) and Mythic (1/24) wildcards, and 53*4 is the number of Rares in a set you need to collect
I usually focus on the middle-to-final stages of design after receiving a vision design handoff