When this creature enters, mill three cards, then put a +1/+1 counter on this creature for each creature card in your graveyard. (To mill three cards, put the top three cards of your library into your graveyard.)
Between stitchers, cultists, and scavengers, corpses are in high demand.
Moldgraf Millipede gets a +1/+1 counter for every creature card in your graveyard, including any creature cards that were already there before you milled three cards.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.