Add a deck. Give your deck a powerful name like, Bruce the Big Bad Basher or Thor the Big Scary God to set the mood and strike fear into your opponents. Add tactics. Things like, Get red mana, Block, or Direct player damage. Expand each tactic to tell us how many matching cards you need by when. Add cards.
Before you draw a card, you must declare how many cards you intend to draw and then draw them randomly (you can use an altered deck of playing cards to simulate the deck). Any cards drawn in excess of this number have no effect. Otherwise, as soon as you draw a card from the deck, its magic takes effect. You must draw each card no more than 1 hour after the previous draw. If you fail to draw.
A deck of many things contains 22 cards. To simulate the magic cards, you may want to use tarot cards, as indicated in the second column of the accompanying table. If no tarot deck is available, substitute ordinary playing cards instead, as indicated in the third column. The effects of each card, summarized on the table, are fully described below.
Pauper Deck Construction. Pauper is a Magic Online format in which all cards used must have been printed at the common rarity in a Magic Online set or product. Other than that, the usual rules for constructed decks apply (a minimum deck size of 60 cards in the main deck, an optional sideboard of up to 15 cards, and so on).
Lands sit in your deck and make up the 40 cards, so you want to have about 17-18 lands in your deck to make sure you draw enough to play cards. In MTG: Arena, the deck builder recommends the lands.
A deck can have any number of cards named Shadowborn Apostle., Sacrifice six creatures named Shadowborn Apostle: Search your library for a Demon creature card and put it onto the battlefield. Then shuffle your library.
Each player may also have a sideboard, which is a group of additional cards the player may use to modify their deck between games of a match. 100.4a In constructed play, a sideboard may contain no more than fifteen cards. The four-card limit (see rule 100.2a) applies to the combined deck and sideboard.
What Alicia says is mostly true, but there are additional rules on the size of the deck. The thing is, you must be able to shuffle the deck quickly and comfortably by hand. Therefore there is a physical limit to the number of cards, and thus plane.