It looks a wee bit expensive for a card that is useless without a specific other card.
I think maybe it would work better as a spell, like to Aflatoxin. Cast it on a creature, and if it dies it turns into a White Blood Cell, perhaps counteracting Aflatoxin. Then White Blood Cell itself can be a misc. card, and the spell could be a Light card, and you could use it on any card on your side as a sort of insurance policy.
Perhaps if you make it a spell also make the White Blood Cell gain +1|+0 when it consumes one. Maybe even +1|+0 and a new 1|3 white blood cell is made.
The only other thing is that I would ditch the multiple times per turn thing, its really unnecessary, and would make multiple White Blood Cells more desirable.
