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 - $14.700
Lightly Played - $11.800
Moderately Played - $10.300
Heavily Played - $8.900
Damaged - $7.400
Near Mint Spanish - $14.700
Lightly Played Spanish - $11.800
Moderately Played Spanish - $10.300
Heavily Played Spanish - $8.900
Damaged Spanish - $7.400
Foil Prices
Near Mint Foil - $33.400
Lightly Played Foil - $26.700
Moderately Played Foil - $23.400
Heavily Played Foil - $20.000
Damaged Foil - $16.700
Near Mint Foil Spanish - $33.400
Lightly Played Foil Spanish - $26.700
Moderately Played Foil Spanish - $23.400
Heavily Played Foil Spanish - $20.000
Damaged Foil Spanish - $16.700