Does Dia and Poison stack?

[Ninja X]

does it?

[Omniblast]

It should. I don't see why not, unless someone has an explaination for it. Same goes for Bio & Poison.

[Taskmage]

They do. It's Dia and Bio that don't stack. Bio will overwrite Dia unless the Dia is a higher tier (Dia III > Bio II).