The tap effect is certainly useful but in most cases it is about the most minor tempo swing on a card
I think this makes Kitsa a potential commander for a deck built around Isochron Scepter and Dramatic Reversal, especially because you dont need both pieces to do the combo
Exiled cards must be used either that turn or before the end of the next turn, otherwise theyre gone forever
As for the card, it's a copy of Akroma's Will, an instant that lets you choose between all your creatures gaining flying, vigilance, and double strike, or lifelink, indestructible, and protection from each color until the end of the turn
These are filled to the brim with effect-granting songs, as well as an army of characters that can quickly Shift onto the board and sing them for free (Cinderella's a typical culprit)
Commander's given this under-supported mechanic a home though, with entire precons based around accumulating and spending energy counters