Fain, the Broker Fain, the Broker does incredible work in the 99 of decks that supply it with fodder, especially ones that spread counters to convert into Treasure, but it rarely does enough to warrant building around it
The "Hex Maniac" Supporter card from the Pokmon TCG XY series expansion Ancient Origins is a great example
One, larger effects tend to be more expensive
Those three could be utility lands like Khalni Garden (comes with sac fodder), Haunted Fengraf (built-in recursion), Mortuary Mire (same), or Bojuka Bog (hose opponents' graveyard strategies, especially if you help them by accident with sth like Ghoulcaller's Bell)
For submissions to this signing event only, CGC is unvaulting the Peach Momoko custom labels for collectors to add to their comics
Playing Sefris gave me an answer: a deck which could play table cop using more exciting tools than a handful of countermagic, while simultaneously building a boardstate that opponents can interact with