Essence Wisp exploit

The essence wisps can be killed like any other enemy. When they reach 0hp a few things happen: the cloud of wisps immediatly drop some essence, they begin an animation where they swarm around eachother, and they fade out to transparency.
Notably the wisps do not actually despawn untill well after they have completely faded out, and in this roughly 2 secon wiindow you can spam the E key to collect the remaining wisps as if you were chasing them.
By running at a wisp, collecting a single essence using E, immediatly killing the cloud with a high level weapon, spamming E to extract additional essencer and collecting all that drops can net 10-15 essence in less than 5 seconds.