User blog comment:B214/Volume 23 discussion blog/@comment-37.8.231.210-20170404182118/@comment-31137559-20170405155017

Sirzechs is basically a god of destruction. He would only have to use that form on someone very powerful. And the person he would fight could probably destroy the landscape around them easily. It's not a matter of control for Sirzechs. It's just him being way too powerful. Boosting that form when it's already OP would probably kill Issei. When powerful beings clash, they can't help but destroying everything around them because they are simply way too powerful.