This potion is made by using super antipoison (3) + clean torstol.
This potion would be called Super poison.
This potion would have a fairly high herblore requirement (85+).
This potions effect lasts for 5 or 6 minutes.
This potion allows all of your attacks to apply poison while the effect is active.
This potions poison effect shouldn't probably be stronger than traditional weapon poison though. Maybe 4.
This btw.

Every combat style already has poison tho. Melee has poisoned weapons, range poisoned arrows and emerald bolts, mage smoke barrage. Quiver and rune bag make it easier to carry stuff that poisons without losing inv space aswell.