Microbe Magnification

Whenever you cast a blue, black and green spell, put a +1/+1 counter on target Germ creature you control.
If you control no germ creatures to put a +1/+1 counter on this way, create a 0/0 black Germ creature token and put a +1/+1 counter on it.
"Didn't think they'd look that terrifying..."
— Delta Demar