Some feedback after my first run (not counting back seating Michael):
Some interesting ideas but the main issue is most the cards are noticeably weaker than base game cards and since the pools are a mix of base game cards and new cards the optimal play is just to pick old cards. (See picture, my build was Shellbo, Chompon, Krono, Snoof)
Here a some comments on the cards I thought are egregiously weak, note I haven't played with most of them yet (partly because I avoid picking bad cards)
Aphrodite - She is like Hazeblazer, but worse somehow?! The base deck has no companion attack increases so realistically to get her effect you need to lower the enemies attack to -1. But there is more! Since if the attack is -1 you only care if the enemy applies some sort of effect.
Ares - To be useful he requires both that he gets kill and he is alone in a row. Compare to a similar base game unit: Yuki. Yuki pays you off for doing something you are already doing and only gives a slightly lower payout (4 timer instead of 3). And I'm saying that as a person who thinks Yuki's payoff usual isn't worth putting such a frail unit in (Ares is basically as frail). Also Ares has anti-synergy with his boon (I want to feed kills to Ares/Mel, can't do both).
Adamant Shard - Compares very unfavorably to Spice Sparklers (granted different tribes).
Thunder Signet - 4 Jolted is really not much. Compare to Hongo's hammer which gives 4 damage after 1 turn and then later an extra 3 damage. Thunder Signet needs the enemy to attack twice to be on par with base Hongo's hammer and Hongo's isn't a card I usually play without synergy.