Beat Loki in < 10 Rounds

[Xargon]

Good to know about feeding the raven thorn sprouts

About Loki: Berserk is very effective here; I found that it gives a big damage boost (far greater than using offensive spells), and defense is not really a problem with Loki. Of course, you have to be using lvl 4 (or below) units, and will probably want to include some archers which get parked on the side and shoot the spawning vikings (so the berserking unit in front of Loki does not get distracted). Teleporting may be necessary as well.
The berserker talent (15% chance for double damage) would probably be nice here as well. In my current playthrough, I got it after maxing out the entire magic talent tree, trading runes with that dwarf, buying some runes and breaking down items (i.e. on Iceland), but it might be nice to get this earlier, if possible.