Bring skulls as drops is amazing but let's be honest, reward shop should've never rewarded players with Pumpkin Lantern, Spider Wings or Kolodion Pet as it devalues Kolodion as monster for actual killing. As pets are not available at wilderness, one can only assume Kolodion won't drop skulls too - then he either must choose places like abyss to farm them or Bosses that are not in wilderness. Tl;dr Those three items should be removed from whole this halloween event, newly hats are fair enough to reach for.

Skeletal version of Raven is amazing, I love it.

As it was per Christmas, so it could be now part two of Draynor quest where you unlock possibility to obtain skulls elsewhere - not only as drops from monsters but randomly, let's say, fishing with it, pickpocketing NPCs or woodcutting trees. Or perhaps, trick or treat players between each other with special items which could use purple sweets or biscuits from clue scrolls. Kinda like idea I would go for but yeah, I take into account it must have take more time and concentration, considering new Boss in wilderness in behind the corner being polished, so it's up to owner of server if it's needed or not.

Continuing first paragraph of whole feedback, Kolodion Spider during this event timer could be minimized to 5-10 minutes gap between re-spawning bringing more action to it. You already saw results with Revenants cave buff. Many players go there now even with minimal risk.

I rate it 8.5/10, being 10 total success.