I ran into the subject situation today on our first play. I went first and rolled an Assistant. I paid the quiddity and summoned the Assistant. As the rules state, I must attack an opponent. With my opponent having no creature with which to defend (they had not taken their first turn yet), how is the attack resolved? I found no mention of this in the rules, nor the FAQ, nor here.
I assume that since there are no defenders, the attack has no effect and the die becomes used.
Thanks in advance!
No effect. The attack is just to destroy other creatures so that they don't stick around long enough to score.