The annoying thing with beyond boosters is that they are only contain seven cards, with the Collector Booster rocking 10 cards
Both its colors and color identity are blue and red, so it cannot be played in decks that use only one of those colors
8 River Song (Showcase Surge Foil) Sing me a song and I'll sell you up the river
Narset Parter of Veils is similarly brutal, her -2 is basically Peer Through Depths, you could argue the case for it being a one mana ability but it would be a very very good one at that
I didnt include Legendary Creatures simply because Im biased, and they are they are my faves, so they would have been half the list
Now that Team Up is out of print, its become one of the most desirable Tag Team cards ever made