We killed Amphitere with a 47 Reaver, 48 Paladin, and 50 Shaman on Gaheris.
The Paladin focused on the adds, while the reaver helped keep aggro off the Shaman by running the AOE chant, and by beating on Amphitere with a fast slasher. The Shaman buffed everyone with Heat resist.
Each tooth that fell out turned into an ancient zombie--we had a total of six, no more than five at once. The biggest source of damage was Amphitere's fire proc.
The zombies dropped normal skins and coin. Amphitere only dropped coin.