Is an Enchantment Creature also an Enchanted Creature? For example, Spiteful Returned states
Whenever Spiteful Returned or enchanted creature attacks, defending player loses 2 life.
If I have Spiteful Returned and Nyxborn Eidolon on the battlefield - both cast as creatures, not bestowed - and attack with both, does the defender lose 2 life or 4 life? Nyxborn Eidolon is an Enchantment Creature, but it has no enchantments on it. Is it technically an enchanted creature?
In addition to the answer you've already gotten, I want to point out that Spiteful Returned doesn't say 'another enchanted creature'; it specifically uses the phrasing 'when enchanted creature attacks'. This refers to the creature that Spiteful Returned is enchanting, and that creature only; if you have Spiteful Returned in play and, say, a Bloodcrazed Hoplite that has a Hopeful Eidolon bestowed onto it, then attacking with the Bloodcrazed Hoplite won't trigger Spiteful Returned's ability.
303.4b The object or player an Aura is attached to is called enchanted. The Aura is attached to, or “enchants,” that object or player.
Since Nyxborn Eidolon has no Auras attached to it, it's not Enchanted.
More importantly, it's not enchanted by Spiteful Returned. Spiteful Returned's triggered ability only triggers when Spiteful Returned or the creature it enchants attacks. It would say "Whenever Spiteful Returned or an enchanted creature attacks" if it was meant to trigger whenever any enchanted creature attacks.
They only lose 2 life. Spiteful Returned is a creature with Bestow. This means that when you cast it you have the option to pay its Bestow cost and when you do that you cast just like an Aura picking a Creature for it to Enchant. When it is an Aura the Creature it is attached to is the "Enchanted Creature", it is never an "Enchanted Creature" if it is not attached to anything and is just an Enchantment Creature.
A creature with bestow gives you the option to cast it as an Aura that enchants a creature, granting that creature its power, toughness, and abilities.
When a card with bestow is in your hand, you have two options: cast it normally for its mana cost, or cast it for its bestow cost. If you cast a bestow card normally, it's an enchantment creature spell that resolves and becomes an enchantment creature on the battlefield. Its bestow ability and its "Enchanted creature gets..." text are ignored.
If you cast a bestow card for its bestow cost, it's never a creature spell. Instead, it's an Aura spell with enchant creature, so you have to target a creature to cast it. If that creature has a heroic ability, this will trigger it, just as any other Aura spell would.
If the target creature leaves the battlefield after you cast a card with bestow as an Aura but before the spell resolves, the Aura spell will resolve as an enchantment creature rather than being countered like a normal Aura spell. If the target creature is still on the battlefield when the Aura spell resolves, it resolves as an Aura enchanting that creature.
While it's enchanting a creature, an Aura with bestow grants the creature the bonuses listed in its text box. If the creature it's enchanting leaves the battlefield for any reason, the Aura immediately becomes an enchantment creature again rather than being put in the graveyard like other Auras.
