Copper Knobberknocker

+7: Gnomish Engineer: Copper grants an ally advantage on the next attack roll they make against a construct of his choice.
+15: Gnomish Wonder: Copper reveals a weakness in a target construct's design, turning the next successful hit against it into a critical hit.
+20: Off Button: Follow my exact instructions! If the next attack roll against a construct hits, it is incapacitated until the end of its next turn.