The Halloween Howling event is already at 100%. The wolf community will never forget...
You can still get rewards for a limited (but now extended) time. Harvest a Grey Wolf during night time (19:00 - 04:00) and pass the Harvest Check before November 13th and you'll unlock:
Halloween Slime Paint
Halloween Clawed Spray
Halloween Frankenpop Camo
Happy hunting and Happy Halloween!