From the eternal set of Teenage Mutant Ninja Turtles : Leonardo, the Balance is white
You must pay a certain amount of ink for your character to be played, but you have to wait for the ink to dry (your next turn) before you can use their abilities (unless the card specifies differently.) Use a character ability that doesnt require them to exert
There are often adhesive residues here, or the adhesive blends with the Blue Core Layer, making it harder to see
Im inclined to say its the latter
I threw together a Golgari (black and green) deck, splashing blue and white in order to play the copy of Atraxa, Grand Unifier that I opened during the event
It is especially nice that he doesnt have to stick to only Flinging the creatures who are attacking, so you can play a new creature and use it to kill off an opposing blocker, suddenly making your attack a real problem for your opponent