Yes the Jotun was the Daemon Prince leading the hordes. The "Stony Bowling Balls" were the Trolls from Frozen, basically they were the ones who summoned the daemons to begin with, and they ended up being exterminated by the Feudal guard and the daemons, with the daemons possessing any dead and turning them into Draugurs (think Tzanngors but they're humans with ice spikes growing out of them in various places).