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 - $11.90
Lightly Played - $9.50
Moderately Played - $8.30
Heavily Played - $7.10
Damaged - $6.00
Near Mint Spanish - $11.90
Lightly Played Spanish - $9.50
Moderately Played Spanish - $8.30
Heavily Played Spanish - $7.10
Damaged Spanish - $6.00
Foil Prices
Near Mint Foil - $46.60
Lightly Played Foil - $37.30
Moderately Played Foil - $32.60
Heavily Played Foil - $28.00
Damaged Foil - $23.30
Near Mint Foil Spanish - $46.60
Lightly Played Foil Spanish - $37.30
Moderately Played Foil Spanish - $32.60
Heavily Played Foil Spanish - $28.00
Damaged Foil Spanish - $23.30