User blog comment:Crimson and Darkness/Volume 25 discussion blog/@comment-24053170-20180716184925/@comment-27973844-20180717010640

The only reason why the power of all of them(the Maous, the Chief-gods etc..)was needed is not only trihexas power but exspecially his hax Regeneration. If Issei would have such Flames, the hax Regeneration of trihexa wouldn't be a Problem anymore. You can compare it to Issei with his SG and without. And About trihexas power itself, we don't know exavtly how strong trihexas raw power is. The author said that a serious(prime)Ophis and GR are able to kill it, even with his hax Regeneration and his hax Regeneration was the only reason why even shiva said it would be impossible for him to kill it. And we Talking About the future Issei who has managed to master his Diabolos Dragon form and also Maybe the powers of Gr and Ophis. To say that he wouldn't be strong enough to kill it even with such Flames is(as far for me)not Right. Also Issei has a hax power himself with the infinity powers he got from ophis.