Hey!
I made a quick little attempt on what you described:
https://www.hiveworkshop.com/pastebin/f123f62dedb49b288cbf2d52723e9b6e16411/
I made a quick little attempt on what you described:
https://www.hiveworkshop.com/pastebin/f123f62dedb49b288cbf2d52723e9b6e16411/
Essentially it's a Starfall-style ability where the Troll Headshrinker (crotchey old potions-master troll) whips out his evil 'Death Rattle' & it begins waving it around. The dark incantations channel out, dealing lots of damage & slowing nearby enemies within it's vile range.
Artistically, I'm thinking of something along the lines of BTNWitchDoctorMasterTraining.blp and/or BTNEntrapmentWard.blp (lemme know if you need pics); a Skull at the end of a staff/stick thing (a "Rattle"), perhaps with something literally rattling around inside it. Glowing eye sockets, evil aura, etc etc. This is the ULTIMATE skill of the hero, and does lots of crazy stuff, so my hope is for it to look impressive, but still fitting to Warcraft 3.
Lemme know if you're interested. : )