Nunu, the Ogdoadic Remnant — Ruling

Effetto 1

The effect that sends a DARK Reptile monster from your Deck to the Graveyard is an Ignition Effect that can be activated in the hand. (Send this card from your hand to the Graveyard as the cost of activating this effect.)

The effect that Special Summons this card is an Ignition Effect that can be activated in the Graveyard. (It can be activated you do not control any monsters, or when you control a face-up "Abhyss" monster.)
This effect finishes resolving by Special Summoning this card from your Graveyard. (This monster is Special Summoned with the part of the effect that banishes it when it leaves the field already applying. Also, the effect that prevents you from Special Summoning monsters other than Reptile monsters begins applying immediately.)