Only 14 are believed to exist, just half of those PSA graded, and this is the only PSA 10
While the term often refers to creatures with activated abilities that tap creatures, like Benalish Trapper and Gideon's Lawmaker, it encompasses ETB triggers, instants, sorceries, and planeswalkers that tap opposing permanents
However, in this instance, the card has holo shift which means missing and/or misaligned areas of the foil layer
While you cant memorise every card, learning the phases of MTG is one of the best ways to improve your skill as a player, helping you to properly plan your turns and know the exact time to drop an instant spell on your opponent to give you the biggest advantage
Obviously, you have to be a pretty serious player to make this kind of investment, but not all of us can afford to spend that kind of money