Its primarily used in combination with other cards which have similar effects and is therefore mainly included in decks which put much emphasis on opposing Character card cost reduction such as the Black Moria and Black Lucci decks
And in addition to all that lovely synergy, Kumena's effects scale really well, drawing cards when the board is small, adding +1/+1 counters to a team that's wide, and growing more and more powerful as you play late game cards like Seedborn MuseSeedborn Muse
The one shortcoming, like many cards that force opponents to sacrifice creatures, is in how they get to make the choice what to sacrifice
Unfortunately, for formats beyond Standard, theres a big emphasis on Lands being able to enter the battlefield untapped
Brawl Legal Vintage Legal Timeless Legal Commander Legal Pauper Not Legal Oathbreaker Legal Penny Not Legal