Carrier Thrall

• WWizards of the Coast2015-08-25
  Official Ruling
  Sacrificing an Eldrazi Scion creature token to add is a mana ability. It doesn't use the stack and can't be responded to.
• WWizards of the Coast2015-08-25
  Official Ruling
  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.
• WWizards of the Coast2015-08-25
  Official Ruling
  Eldrazi Scions are similar to Eldrazi Spawn, seen in the Zendikar block. Note that Eldrazi Scions are 1/1, not 0/1.
• WWizards of the Coast2015-08-25
  Official Ruling
  Eldrazi and Scion are each separate creature types. Anything that affects Eldrazi will affect these tokens, for example.

Rulings via Scryfall