"Go and tell him that I will be coming for his head.", Jay said this directly as if he had no intention of granting him mercy.
The same applied to those who allied with him. He had already thought about leaving the rest to the generals and Alon who could do a pretty good job in stopping them for sure.
All that Jay had to do was prevent himself from getting killed and even if he got killed, he should prevent from panicking after being revived on his own.
'Yes, it's a showdown between us…', he said to himself in his mind.
Right after that, he marched out as if he literally meant what he thought.
He dictated whatever was on his mind to Alon who wrote it down in a letter and used his familiar – a two-headed crow – to go and give it to Arcane.
Of course, it would be rather safer for familiars to go and deliver such stuff rather than actually letting demons go who could end up showing tons of emotions and would get killed.