User blog comment:Crimson and Darkness/Volume 25 discussion blog/@comment-34061653-20180506195121/@comment-34061653-20180507111201

Someone on aniemsuki brought this up and I think it's possible

"Crom reverts to his true Dragon form and yes Crom did admit there isn't much of a difference in power between his human and Dragon form except the intensity of his attacks but every little bit helps. Plus I think will be more durable in his Dragon form. Now remember Crom fighting Vali? He did so without a promotion from Rias. If Crom fought with promotion to Queen then Crom would've had a serious advantage over Vali. Now could Crom.beat Ddraig and Issei like that? Not really but Ddraig has a time limit so the way I see it.

Crom+reverts to Dragon form+ Promotion to queen and hold out until Ddraig's time limit. Now yes, receiving a promotion goes against Crom's pride because he likes to fight with his own strength but I see no other way for Rias to deal with Ddraig."