Whichever part of the effect you care about, having a cheap source of it at the beginning of each turn makes your deck tick
Relic of Progenitus and Leyline of the Void keep the graveyard clear, which can be a problem for a deck that focuses on controlling the opponents hand
Note that this is only true of X- spells , but X is treated as 0 for permanents on the battlefield
The most efficient way to flood the board with artifacts is to lean into a Tokens subtheme: cards like Forensic Gadgeteer, Sai, Master Thopterist, Mirrodin Besieged, and Efficient Construction all make an artifact whenever we cast an artifact, simple
Either way, Liliana's Contract is a solid card, allowing you to draw four cards and lose 4 life, and you can blink it too