Greta, Sweettooth Scourge

When Greta enters, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")
{G}, Sacrifice a Food: Put a +1/+1 counter on target creature. Activate only as a sorcery.
{1}{B}, Sacrifice a Food: You draw a card and you lose 1 life.

Peregrin Took

If one or more tokens would be created under your control, those tokens plus an additional Food token are created instead. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")
Sacrifice three Foods: Draw a card.

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.