Poison Attack

Poison Attack is a gem effect in Xenoblade Chronicles and Future Connected. It grants a percentage chance that the user's will inflict poison for 10 seconds, dealing extra  every 2 seconds (for a total of 5 extra hits). Unlike the debuff's normal effect, the damage done is equal to the gem's value, rather than based on the initial damage dealt.

Overview
Poison Attack is just an extra source of damage; it can be placed on anyone who wants to deal more damage without having to worry about extra (as it's a debuff). It's the best of the four damage-debuff-auto-attack gems by a significant margin, dealing the most damage both per-gem and at the combined cap, but is also by far the hardest to get.

In the original version, Poison Attack works against Mechon armour, dealing its full damage. In the Definitive Edition, it does not trigger at all.