On the latest ESO live, the developers mentioned that they will soon be adding four new AvA skills into the game, one of which is designed to fight Zergs in PvP. They noted that people like to group up, so the skill will be something like the Sorceror curse skill in that you can pop it on someone and then it will explode, but it will hit everyone near that enemy. One of the morphs would make the skill unpurgable (or would damage anyone who tried to purge it).

Source: At 57:50 of the latest ESO live:

http://www.twitch.tv/zenimaxonlinestudios/b/581386909

This seems to me a step forward, but personally, I would prefer that they bring this in at the same time as they nerf oils, because oil often serves much the same purpose (i.e. giving you a chance vs. Zergs). So wouldn't it be best to wait until after these new skills are in to nerf oil, or to time it so that oil is nerfed at the same time that these new skills are introduced, so that we still have some chance against the Zerg trains currently plaguing Cyrodiil? What do you think?