If I recall there are four, the Piracy first, Reconnaissance Mission with cycling, the Bident above that can be tapped with two mana on an opposing turn to force them to attack and then the recently printed Vehicle called The Indomitable
Four mana and two forages to get a 4/3 and a 3/3 is a good deal, a strong way to catch up or get ahead with your board presence
Sphinx's Tutelage, for example, could mill a lot of cards from a mono-color deck, just for drawing a single card
More recently, cards like Oko, Thief of Crowns and Once Upon A Time have been spotlit in discussions on pushing card mechanics a little too far, with both cards needing bans across several formats to keep the game healthy
I could talk a bit more about the effect that Aminatou, the Fateshifter and crew had on the game
This is possible, but it's not particularly likely