Drowner of Hope

Eldrazi and Scion are each separate creature types. Anything that affects Eldrazi will affect these tokens, for example.

Cards with devoid use frames that are variations of the transparent frame traditionally used for Eldrazi. The top part of the card features some color over a background based on the texture of the hedrons that once imprisoned the Eldrazi. This coloration is intended to aid deckbuilding and game play.

Sacrificing an Eldrazi Scion creature token to add {C} is a mana ability. It doesn't use the stack and can't be responded to.

Devoid works in all zones, not just on the battlefield.

Some instants and sorceries that create Eldrazi Scions require targets. If all targets for such a spell have become illegal by the time that spell tries to resolve, the spell won't resolve and none of its effects will happen. You won't get any Eldrazi Scions.

You can't sacrifice the same permanent to pay two different costs. Notably, if you sacrifice an Eldrazi Scion to activate the last ability of Drowner of Hope, you won't add {C}.

You can sacrifice any Eldrazi Scion to activate Drowner of Hope's last ability, not just one created by Drowner of Hope.