Ultimately, this is mostly irrelevant due to how weak the Goblin Trapsmith is, but it's good to know nonetheless.
The Warrior gets to roll two dice in battle and use the higher attack roll. The Goblin Trapsmith forces you to roll one extra die for your attack roll and use the lowest result.
How many dice does the Warrior roll against the Goblin Trapsmith and which result does he pick?
Does he still roll two dice? That seems to negate the Warrior's ability to roll extra dice.
Does he roll three dice? That seems to match the language of the card, "Roll one extra die."
Does he roll four dice? That would be two dice for one of his attack rolls and two dice for the other. That seems to be a bit of a stretch, but within the realm of possibility.
And then which result does he pick? His special ability lets him pick the highest. The Goblin Trapsmith says he must pick the lowest. I know that there's an priority to these things and that it's in the rule book. I'm short on time at the moment, so I'll accept that some people will probably yell at me over this.
This came up in our game last night and we were trying to figure it out until my wife realized that she had strength 7. Against a strength 1 she cannot lose.