I was doing a quest in Dustwallow Marsh today called Corrosion Prevention.
You have to charge some oozes to make them blow up. I noticed that if i attacked the ooze first then used the item to kill it i would still get xp and loot.
It means i could kill the oozes in like 6 seconds, making that a bit faster than usual and i found it to be a useful way to grind plus you have no downtime. Even though i completed the quest i was still able to use the item to kill the oozes.
Been grinding them for some time now and i recommend that if anyone should come by at the appropriate level, take yourself some time to get some fast xp. Besides you get full xp for the kills.
Screens:
If possible, notice my enrage buff and you'll see how few seconds it took me to kill it. Hope its any help.