Each creature gets +1/+1 for each other creature on the battlefield that shares at least one creature type with it. (For example, if two Goblin Warriors and a Goblin Shaman are on the battlefield, each gets +2/+2.)
"Hup, two, three, four, Dunno how to count no more." —Mogg march
Near Mint - $26.00
Near Mint Non-English - $26.00
Lightly Played - $24.75
Lightly Played Non-English - $24.75
Moderately Played - $20.75
Moderately Played Non-English - $20.75
Heavily Played - $15.50
Heavily Played Non-English - $15.50
Damaged - $13.00
Damaged Non-English - $13.00