<P> In most Constructed formats, there exists a list of individual cards which have been "restricted" (the card is limited to a single copy per deck) or "banned" (the card is no longer legal for tournament play). These limitations are usually for balance of power reasons, but have been occasionally made because of gameplay mechanics . </P> <P> In "Limited" tournament formats, a small number of cards are opened for play from booster packs or tournament packs, and a minimum deck size of forty cards is enforced . The most popular limited format is draft, in which players open a booster pack, choose a card from it, and pass it to the player seated next to them . This continues until all the cards have been picked, and then a new pack is opened . Three packs are opened altogether, and the direction of passing alternates left - right - left . </P> <P> Deck building requires strategy as players must choose among thousands of cards which they want to play . This requires players to evaluate the power of their cards, as well as the possible synergies between them, and their possible interactions with the cards they expect to play against (this "metagame" can vary in different locations or time periods). The choice of cards is usually narrowed by the player deciding which colors they want to include in the deck . This decision is a key part of creating a deck . In general, reducing the number of colors used increases the consistency of play and the probability of drawing the lands needed to cast one's spells, at the expense of restricting the range of tactics available to the player . </P> <P> Most spells come in one of five colors . The colors can be seen on the back of the cards, in a pentagonal design, called the "Color Wheel" or "Color Pie". Clockwise from the top, they are: white (W), blue (U), black (B), red (R), and green (G). To play a spell of a given color, at least one mana of that color is required . This mana is normally generated by a basic land: plains for white, island for blue, swamp for black, mountain for red, and forest for green . The balances and distinctions among the five colors form one of the defining aspects of the game . Each color has strengths and weaknesses based on the "style" of magic it represents . </P>

How many different magic the gathering cards are there