Whenever you cast a noncreature spell, put an oil counter on Mercurial Spelldancer
Winter Orb is a "stax" artifact that severely limits each player's ability to untap cards during their untap step, and that will slow the game down
It gets even better when partnered with Armix, Filigree Thrasher or Glacian, Powerstone Engineer
Granted, making a copy of a unique creature is very different from the same vampire token over and over, but it proved to be a hindrance that slowed the deck down enough that it has never felt like a pillar of the format
A few weeks ago, I wrote a tech piece about sideboarding against the then-top decks
As such, this would be very playable in Limited, and might even replace a few of its similar counterparts in niche Standard decks