This can be worth it depending on the situation, but otherwise, the effect is just a good match for the unity seen in the art
Nothing about this builds up anything, just eats away at resources, whether your opponents or your own
Charmbreaker Devils There are a lot of prowess-like pumps in MTG, but the +4/0 of Charmbreaker Devils is elite
For anything where different rarities are mixed, Wizards uses the booster pack model of distribution, as far as we know
Red Manga Rare Keeping the best for last, One Piece TCG released the Red Manga (an alternate color of the existing Manga Rare) for OP13, with the lowest pull rate ever an average of 0.07%
All in all I am mostly happy with the economy of the game so far