I agree in that I prefer "badly poisoned".
However, if "Toxic poisoned" is being considered, it may help to present an example sentence for reference. It seems like, instead of using "Toxic poisoned" like a verb, it would be better to just say "poisoned by Toxic / Toxic Spikes". Saying so and so is "Toxic poisoned" (using the phrase like an adjective) just sounds weird.
Strictly speaking, I believe "Toxic" in "Toxic poison" should be capitalized, as it is a proper adjective.