True Believer

You have shroud. (You can't be the target of spells or abilities.)

Platinum Angel

Flying
You can't lose the game and your opponents can't win the game.

Estrid, the Masked

+2: Untap each enchanted permanent you control.
−1: Create a white Aura enchantment token named Mask attached to another target permanent. The token has enchant permanent and umbra armor.
−7: Mill seven cards. Return all non-Aura enchantment cards from your graveyard to the battlefield, then do the same for Aura cards.
Estrid, the Masked can be your commander.

Sterling Grove

Other enchantments you control have shroud. (They can't be the targets of spells or abilities.)
{1}, Sacrifice this enchantment: Search your library for an enchantment card, reveal it, then shuffle and put that card on top.

Enchanted Evening

All permanents are enchantments in addition to their other types.

Greater Auramancy

Other enchantments you control have shroud. (A permanent with shroud can't be the target of spells or abilities.)
Enchanted creatures you control have shroud.

Avacyn, Angel of Hope

Flying, vigilance, indestructible
Other permanents you control have indestructible.