@Enjou, I think it's a bad idea to send Jacob to Asgard, for pretty much the same reasons why Nurgle said it was a good idea: Jacob is good at small unit tactics, stealth, and assassinating heroes. The battle for Asgard will be a full on World War. Jacob's proficiency at small unit tactics will not make any difference there. The battle will be waged by massive armies duking it out, not individual heroes duelling each other. Hordes counter heroes, and Jacob is a hero specialised in killing heroes, not hordes, so it's especially bad for him.
Send him to Muspelheim. The battlefields are smaller, so small unit tactics will be more important. As the update itself said, the battle for Muspelheim will be one of elites, and heroes counter elites, and with elites come heroes to lead them, so Jacob's status as hero and proficiency at killing heroes will be most useful here. Finally, Muspelheim is a lot of space stations. You know Genestealers? Or the aliens from Alien/Aliens? That's Jacob. He's the one crawling through the side passages, ambushing enemies and causing lots of fear and damage. There's no substantial opportunity for his stealth proficiency to come to the fore in Asgard, but there's many opportunities in Muspelheim.