Maybe its just me but this spell does no where near 1500 damage. The first tick starts at 5, and the last tick ends at 43. It increases 2 damage with each tick. According to my calculations that is around 540 damage. I have never noticed a tick of this dot causing it to break root, so i dont think it does. This spell is basically useless as far as i am concerned with a few exceptions. This spell stacks with the other shaman root spells, and it always lasts the full duration, unless broken by damage.
Having the ability to have 2 roots on a mob can be quite helpful when dealing with high mr mobs that root wont usually stick on. Of course most of them time you are dealing with highly mr mobs, they will probably summon from the damage of grasp of spirits, making it useless once again. With all that being said, i do think the mana cost is a bit extreme.
it used to last the full duration.. but it no longer last the full duration.... and when trying to use it in WW now adays is useless....casted on a dragon last for prob less then 30 sec... i seriously think the dot on the root broke the root..because i didnt cast any thing eles after...same thing happens on other mobs every now and then when soloing...