It does direct earth damage in a small aoe, applies oiled and if you land it on fire(in my case 99% of the time :)) burns/blocks LoS. I think it's really good and novice earth slots aren't that constrained early on anyway.
I honestly thought it was better in the original version simply because it used to be able to knockdown and poison. Now it just feels like a more expensive midnight oil. The damage area isn't even as big as the oil puddle it makes.