"If you are strong enough to do so, then do as you wish, but only if Mars allows you to, and under no circumstances are you allowed to manipulate Mars into doing that."
Surtur frowned.
"Why are you setting me free? The people of this world sealed me here to use me to fight in Holy War."
"I'll handle the Holy War. You should instead tell me if you accept my offer or not."
"Can I have some time to think?"
"Sure."
Neo used Nightmare Element on Surtur.
Inside the Nightmare, the creator of Nightmare could control the relative time to some degree.
Surtur was able to think through this decision for five days when in reality only five seconds had passed.
Neo closed the Nightmare, allowing Surtur to think properly again.
"I'll accept your offer."
"Got it."
Before setting Surtur free, he put his Intent inside Surtur's body along with a single bolt of Death Element.
