Grimgrin

[Quackmaster5]

I need a ruling. Can I repeatedly sac {grave crawler } to feed {grimgrin, corpseborn} even if he is already untapped? And if so, can I only bring back grave crawler during my turn? Or could I do it at the end of the opponents turn?

Sorry if this has already been asked. I can't find a discussion on it.

[BadLuckIrish]

You may sac anything anytime with his ability even if he is untap. Gracecrawler ability allows you to cast him anytime you coild cast a creature (without flash) from your hand

[Quackmaster5]

Thanks. I wasn't sure he would have to be tapped as a requirement.

And I wasn't sure, since it's an activated ability, that it had instant-speed or not.

So the remedy would be to just sac and bring back {grave crawler} a bunch of times  during my main phase. Now if he comes back from the graveyard, would grave crawler then have summoning sickness?

[BadLuckIrish]

Yes for it would be the first time you have him.
{Havengul Lich} allows you to cast him for 1 anytime btw...

[loop-s-pool]

Not anytime, only your main phases and it would also be 1B.