Your search for "Rotting Mastodon 87" revealed the following:
Rotting Mastodon (KTK) from Khans of Tarkir, available at 401 Games Canada. Rarity: Common Finish: Normal Artist: Nils Hamm
Rotting Mastodon (Foil) (KTK) from Khans of Tarkir, available at 401 Games Canada. Rarity: Common Finish: Foil Artist: Nils Hamm