As a group, decks using companions have too high of win rates and metagame share in Standard, Pioneer, and Modern, and have already necessitated bans in Legacy and Vintage
While most cards are reprints or support cards, the big draw lies in Charizard V and Charizard VMAX chase cards, as well as strong V/VMAX cards like Alcremie, Incineroar, and Hatterene
The vibe is danger: cosmic danger, or cosmic madness
One possible solution is to use a standardized measure of the compound mean difference that is, the standardized measure of distance between the means of two Pr ( x i ) distributions.
In most cases, you want some lower to mana-value cards (to ensure you have things to play early) and some higher mana-value cards so you'll have more powerful stuff as the game goes on
It started a few weeks back with Kozilek, the Great Distortion, but the trend has kept up