I think anet just needs to get rid of the getting the essences done before the event ends thing. It's needlessly confusing and frustrating. After trying to get this done all day between separate maps and failing because one - no more spawn and you don't get enough essences, two - dealing with the constant interrupts and knockdowns, and three - it only takes one "helpful" or troll person to kill that last mob to ruin the whole achievement. All the other Koda events are challenging in their own right, and are fine. Its just THIS ONE that is obtuse and frustrating. There's nothing saying that the essences have to be done before the event, and even the title isn't even relevant to what you need to be doing, so how is one supposed to figure out what's happening? Just my two cents. :)