For a long time, it wasnt really possible to build a good Exava deck because there werent enough cards with her identity that did stuff with counters
The combination loses counterspells and card selection, making it more vulnerable to combo strategies
If you do, put a permanent card from among them onto the battlefield with a finality counter on it
Its not enough to bounce their cards with a Teferi, Time Raveler or a Brazen Borrower, as many have haste or enter-the-battlefield effects that minimize your tempo plays
As further cards are released and there are more deckbuilding options, these color identities will likely become more evident
While I couldn't resist bringing an aggro group hug deck to the table, as I opened the article saying, there's innumerable ways you can go with Ms