Wall of Poison Gas vs Veteran's Belt

[sIKE]

From the Codex:

Critical Damage (Game Term)
Critical damage bypasses Armor (Armor does not reduce the damage dealt). Critical damage is shown as numbers inside a starburst on the attack dice.

So an attack with the Critical Damage trait will roll dice as normal (Roll Dice Step) and any damage rolled will be applied as Critical Damage.

[Zuberi]

@Kaarin
Another misleading question. Attack traits are always in effect. An attack with Piercing +3 always has Piercing +3 even when it's not attacking. It just doesn't matter until you check it against a target's armor. An attack that has Unavoidable is always Unavoidable, it just doesn't matter until you check for defenses. The damage from an attack that deals Critical Damage is always critical. There is no point at which it is converted and you'll take it into account whenever it happens to matter.