25 Aug 2015
Eldrazi Scions are similar to Eldrazi Spawn, seen in the Zendikar block. Note that Eldrazi Scions are 1/1, not 0/1.
25 Aug 2015
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.
25 Aug 2015
Eldrazi and Scion are each separate creature types. Anything that affects Eldrazi will affect these tokens, for example.
25 Aug 2015
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.