Vigilance
Sacrifice two Eldrazi Scions: Return Deathless Behemoth from your graveyard to your hand. Activate only as a sorcery.
Eldrazi Scions are similar to Eldrazi Spawn, seen in the Zendikar block. Note that Eldrazi Scions are 1/1, not 0/1.
Eldrazi and Scion are each separate creature types. Anything that affects Eldrazi will affect these tokens, for example.
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.
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.