Originally Posted by WadeB
So I was just curious about how many legendary creatures you can have in a deck. I haven't seen any rules about it and my opinion is that you can only have one. Thanks for any input.
You can only have one on the battlefield. The reason for this is that if there are two are more legendary permanents with the same name, they all die.
You can have up to four copies of such a card in your deck, though, just like most cards.
100.2a In constructed play (a way of playing in which each player creates his or her own deck ahead of time), each deck must contain at least sixty cards. A constructed deck may contain any number of basic land cards and no more than four of any card with a particular English name other than basic land cards.
704.5k If two or more legendary permanents with the same name are on the battlefield, all are put into their owners’ graveyards. This is called the “legend rule.” If only one of those permanents is legendary, this rule doesn’t apply.