Defensive Duelist Eval Script
Tick "Show in Activated Abilities list"
Run Post-Attributes
Code:
doneif (tagis[Helper.ShowSpec] = 0)
doneif (tagis[Helper.Disable] <> 0)
doneif (field[abilActive].value = 0)
hero.childfound[ArmorClass].field[Bonus].value += hero.child[ProfBonus].field[tProfBonus].value
That last bit adds the current Proficiency bonus to AC for when it's active.