Mirroring Life vs. Death

Thinking about ways to mechanically represent the growing conflict between the "pure" creatures and people represented in green and white versus the plague-afflicted black and blue folks with mechanics that aren't necessarily mutate or reanimation.

Here's a common mirrored pair in green and black.

The rules text is maybe a little more complicated than it needs to be by referring to the battlefield rather than just creatures you control. But I wanted to make sure it was very clear what triggered the bonuses.

There is a question as to whether the mechanics are too complex for common. I don't think they are. It's very easy to check and not confusing.