I'm really happy druids finally got a thorns that was worth casting. I'm not really sure what Blizzard initially had thought with thorns, it's always been like some sort of bad retribution aura. First of all you had to recast it every 10 minutes and it didn't do nearly as good damage. But as usual Blizzard give druids something that is similar to an already existant spell, only not nearly as good. Until now!
Thorns is still similiar to another spell, but maybe that's unavoidable by now. Any spell to any class will be pretty similar to some other. It now works like a kind of Recklessness. Short duration, high in damage, dealing damage to anyone who's attacking (except casters). Unlike Recklessness, and still similar to Retribution Aura, it still seems to scale with spellpower. This means a resto/boomkin druids thorns can deal som 2-3k per hit while feral cat/bear druids deal around base damage which is some 700-800 damage per hit.
There are many great utilities for a skill like this. Bears can pop it before running into a tank encounter for extra threat. Pvp-druids can pop this to make people less eager to burn you down. This skill has drawbacks however. It is completely awesome, and I am totally glad druids have it. But...
Blizzard also gave this skill to any mob out there who casts thorns. Sometimes when they revamp an old spell, they let mobs keep the old version. This doesn't seem to be the case with thorns however. Any mobs who casts thorns on themselves now seem to use the revamped version. Why is this a problem?
Because thorns is extremely strong! It makes lowbie mobs (those I have encountered so far with this skill) way overpowered for their level. I'll give you an example;
I ran in, swinging my little axe wildly, hoping for the ugly troll to die. Suddenly I was the one who was dead. I blinked in confusion. But I had been on max health just a second ago. Seriously! Ok, maybe I was wrong, maybe I was low on health for some reason. Retry, same result. What the... Something's not right here.
This time I started hitting him a little more careful, watchful for any sign of him using some sort of doomskill which seemed to oneshot me. And then it came. Thorns! Ok let's recap quickly - I have 200 hp. Thorns did 50 damage to me every time I hit the mob. 50 damage! That meant I could kill myself within 2 seconds by using Crusader Strike, Judgement and melee swings. The mob hit for around 20 damage every other second, giving him some 10 dps. Thorns on the other hand could deal 100-200 damage to me in a matter of seconds.
There was no alternative. I had to give up hitting the mob as soon as he used thorns. Which meant I had to stare angrily at him for 20 seconds (!), waiting for it to drop off before I could start hitting him again. I used Hammer of Justice to buy myself some time, but it still meant that each Snowstrider fought got some 15 seconds of free blows before I could retaliate. Do you know how long 20 seconds of in-action per mob feels? Quite long I can tell you. Especially since it made me nearly die before I could start defending myself. I am sure this isn't intended.
It is merely interesting to see what changing something at high-end can affect in other areas of the game. You know the whole saying about the "wings of a butterfly..." comes to mind here. I suppose Blizzard weren't joking when they said balancing skills wasn't easy!