Their Number Is Legion

Create X tapped 2/2 black Necron Warrior artifact creature tokens, then you gain life equal to the number of artifacts you control. Exile Their Number Is Legion.
You may cast this card from your graveyard.

Ygra, Eater of All

Ward—Sacrifice a Food.
Other creatures are Food artifacts in addition to their other types and have "{2}, {T}, Sacrifice this permanent: You gain 3 life."
Whenever a Food is put into a graveyard from the battlefield, put two +1/+1 counters on Ygra.

Cranial Plating

Equipped creature gets +1/+0 for each artifact you control.
{B}{B}: Attach this Equipment to target creature you control.
Equip {1}

Fomori Vault

{T}: Add {C}.
{3}, {T}, Discard a card: Look at the top X cards of your library, where X is the number of artifacts you control. Put one of those cards into your hand and the rest on the bottom of your library in a random order.