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 - $14.300
Lightly Played - $11.400
Moderately Played - $10.000
Heavily Played - $8.600
Damaged - $7.200
Near Mint Spanish - $14.300
Lightly Played Spanish - $11.400
Moderately Played Spanish - $10.000
Heavily Played Spanish - $8.600
Damaged Spanish - $7.200
Foil Prices
Near Mint Foil - $31.500
Lightly Played Foil - $25.200
Moderately Played Foil - $22.100
Heavily Played Foil - $18.900
Damaged Foil - $15.800
Near Mint Foil Spanish - $31.500
Lightly Played Foil Spanish - $25.200
Moderately Played Foil Spanish - $22.100
Heavily Played Foil Spanish - $18.900
Damaged Foil Spanish - $15.800