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 - $13.900
Lightly Played - $11.100
Moderately Played - $9.700
Heavily Played - $8.400
Damaged - $7.000
Near Mint Spanish - $13.900
Lightly Played Spanish - $11.100
Moderately Played Spanish - $9.700
Heavily Played Spanish - $8.400
Damaged Spanish - $7.000
Foil Prices
Near Mint Foil - $45.100
Lightly Played Foil - $36.100
Moderately Played Foil - $31.600
Heavily Played Foil - $27.100
Damaged Foil - $22.600
Near Mint Foil Spanish - $45.100
Lightly Played Foil Spanish - $36.100
Moderately Played Foil Spanish - $31.600
Heavily Played Foil Spanish - $27.100
Damaged Foil Spanish - $22.600