hyena's!

[BB Shockwave]

I used Hyenas for quite some time on the first continent. They are fragile (too small HP for Level 2 unit, compare them with Goblins...) but do great damage.

And their specials come in handy - night attack means they are more powerfull underground (day/night cycles are so slow you cannot really count on this factor) and scavenger means their otherwise average speed can be more (4-5) and they can reach enemies without the use of a haste spell, if there is a dead body nearby. You'll need powerfull archers for that, though.

Overall - they are good skirmishers alongside a strong tank like Ancient Bears - use hit and run tactics, and never attack an enemy who has still retaliation left, as they cannot take damage well. Like all animals, they too have -10% fire resistance so keep that in mind, Fire Dragonflies can be problematic.

I used them as an on again, off again reserve troop up until I got to Kordar. Sadly, my losses have started to get high of them, so I left them - without resurrection, you are bound to lose quite a few of them every battle, especially if the enemy gets in a few criticals.

Thorns - they are abysmal. Hunters are very bad archers, too low attack to ever cause good damage, Warriors are fast but that's all that's good about them. They have some immunities, but face it - on the first continents you'll use them, no enemy hero will use Blind anyway. And the -100% fire res. is a huge setback - Fire Dragonflies, Alchemists are things you'll encounter often sadly. The Royal Thorn would be a good unit early on - but most likely you won't get any until you get to the Elves. Unless you want to use them in an all-elven army, where they get good synergies from Dryads, they are a liability, especially when fighting Dragons (trust me, I tried - the AI goes straight for your thorns with Dragons). Royal Thorns are mediocre archers (Elves are better) and great for summoning fodder, but Dryads can summon Thorns too and Elven Hunters can shoot better.