Creature - Rat 2/2, 1BB (3) Relentless Rats gets +1/+1 for each other creature on the battlefield named Relentless Rats. A deck can have any number of cards named Relentless Rats.1
Illus. Thomas M. Baxa
12/1/2004: Yes, you're allowed to play a deck consisting of sixty Relentless Rats and nothing else.
12/1/2004: This card's text applies even in Constructed-tournament play. It overrides the normal limit of four of an individual card.
12/1/2004: This card's text does not override other format-imposed restrictions on the number of cards. For example, in a Highlander format, you would still only be allowed one Relentless Rat.