Altar of the Goyf

ゴイフの祭壇 (Altar of the Goyf) (ja)

Kindred Artifact - Lhurgoyf (CMC 5)
Whenever a creature you control attacks alone, it gets +X/+X until end of turn, where X is the number of card types among cards in all graveyards.
Lhurgoyf creatures you control have trample.