Graverobber

[Cal8301]

If you play {nezumi graverobber}
http://magiccards.info/cmd/en/92a.html
and that have no graveyard does he auto flip? I don't think he does I think it's part of his effect when you pay the mana not a static effect but I looked it up and there's no ruling on it. So I was just courious.

[BlackJester]

{Nighteyes, the Desecrator}

There needs to be at least one card in that graveyard for you to target. If you can't target a card, you can activate the ability.

Ideally, you want to target the only card left in a graveyard for him to flip.

[KulrathKnight]

In order to turn the creature into {Nighteyes the Desecrator}, you need to pay its activated ability cost, AND remove the last card from an opponent's graveyard (same reason {Chalice of Life} doesn't auto-flip to {Chalice of Death} if it enters the battlefield after you already have 30+ life).

If there are no cards to target for the Graverobber, you can't flip it.