2015-08-25 : Eldrazi Scions are similar to Eldrazi Spawn, seen in the Zendikar block. Note that Eldrazi Scions are 1/1, not 0/1.

2015-08-25 : Eldrazi and Scion are each separate creature types. Anything that affects Eldrazi will affect these tokens, for example.

2015-08-25 : Sacrificing an Eldrazi Scion creature token to add {C} to your mana pool is a mana ability. It doesn’t use the stack and can’t be responded to.

2015-08-25 : 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.