[KissBlade]

Only their sacreds really. Come early mid game, a good Helheim player at war with you will literally be all over your empire except where your main army is. Standard anti raiding squads won't work because Helheim raiders crushes them. You can tell you're fighting a good helheim when your chokepoints simply don't work. Between flying Dis + Valk raiders with stealthy helherdlings, it's a toughie for most nations. Especially if research is kept at standard pace. Evocation spells DO work, but as the above poster, the harder part is actually catching them in the act. Caelum is actually pretty strong, lightning bolt => thunder strike is a legitimate counter against Helheim as well as your standard mammoth/wingless group to hold them off.

Judging from your dismissal of magic though, that is probably why you're having trouble. As numerous people pointed out in this thread, magic plays a very large part of this game. In fact, the reason you're probably having a tough time is because you're dismissing it so easily. Especially because Caelum is a magic nation!