From Justin's website- winner of WCOOP main event

[Zybomb]

You make up your own deck of the cards that you own. There are creatures with attack power and defense power, spells that can inflict damage to creatures or an opponent. All creatures spells and other playable cards require (if i remember its called mana or something like it) There are 5 colors and mana of each color. So spell A may cost 2 white mana and 3 of any other mana (5 total) to cast, so you need to have that much mana on the table to cast it. You can only play one mana per turn.

There is a good portion of the game that is won with a deck alone. Knowing how your deck works, and how to correctly set up a winning deck is the biggest part. The other half is knowing how to use your deck, and how to adapt to the other persons deck (games are played best of 3) and anticipating opponents moves.