On the front, Cosima is a little hard to parse, but essentially, she works like so: at the beginning of your upkeep, you exile Cosima
Not only that, but when a ninja - which they are - deals combat damage to an opponent, you get to reveal the top card of your library, put it into your hand and then each opponent loses life equal to that cards mana value
While it isn't game breaking, playing Naban, Dean of Iteration on Turn 2 into Sunscourge Champion on Turn 3 to gain four life is a nice value start for a Naban deck, especially considering that Sunscourge Champion can come back to gain eight life later in the game thanks to eternalize
You can use the ability to destroy your opponents army or take away all of their land
It is only played in one deck in that format, and that is unlikely to change
ITS NOT EASY BEING A HERO Unfortunately, the unique two-part design of these creatures prevents some possible lines we could take to squeeze extra value out of them