It's the only thing that can. The miasma cannon is a relic heavy venom cannon, and tyrants are the only character that can equip a heavy venom cannon.
I don't think you can put both the miasma cannon and a regular
HVC on a tyrant though, as you're limited to one of the big monstrous bio-cannons. I'm not quite sure if that's what this list is saying, or if it's just listing the relic upgrade next to the original gun. Although if that's the case, what's the second weapon on the tyrant?