User blog comment:B214/Volume 23 discussion blog/@comment-31137559-20170414184220/@comment-87.8.235.3-20170414211033

Diehauser was easily able to negate Boost, I think that doing the same with Transfer would be easy for him.

Sairaorg doesn't use his touki as a shield or a barrier, he uses it to increase his own body strenght, so I don't think Penetrate would be useful in this case.

By the way Issei can give to Xenovia the ability of his Boosted Gear using the wyverns to give her an armor, as he did in Vol 23.

I think that the best offensive Issei could realize would be dragonification on his whole body and then covering himself with the Infernal Flames (since his own body is made of Great Red flesh, who is immune to that fire, he would not suffer any damage) and attack with his own body. It would be a deadly power for sure, and he could add to the flames the Penetrate bypass any defense.