Ramosian Greatsword (March of the Machine)

Artifact — Equipment - Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Equipped creature gets +3/+1 and has trample.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)