It essentially allows you to steal the activated abilities of creatures in any graveyard and give them to all of your creatures, so long as they have +1/+1 counters on them
Chief among them are Collector Boosters and Collector Editions of Commander Decks, which are sold out, but are selling at a mighty high markup on the secondary market right now
This five-ability 7-drop with seven loyalty is next on the list
Shard of the Nightbringer is a great late game big burn spell, though it only hits one player and it's on cast, even though it's on a creature
There are only a few banned cards for MTG Vintage: Chaos Orb Falling Star Shahrazad Besides banned cards, there are also a number of restricted cards in MTG Vintage
At its best, though, playing a couple of these in a row will allow you to become essentially unbeatable very quickly