Sweet art. Not sure what to think of it yet.
and
are a kind of strange combo most of the time. I could see the upped version being OP in Discord-BlackHole decks. I most like the idea of double poison, and I think the unupped would be sweet in a lot of rainbows: powerful, but hindered in terms of its CC ability by the same slowness that affects Plague.
I think you should make your mind up on the radiation thing. Just poison sounds fair to me, in which case I would just phrase it like