Eidolon of Countless Battles

Bestow {2}{W}{W} (If you cast this card for its bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached to a creature.)
Eidolon of Countless Battles and enchanted creature each get +1/+1 for each creature you control and +1/+1 for each Aura you control.

Silent Arbiter

No more than one creature can attack each combat.
No more than one creature can block each combat.

Nykthos Paragon

Whenever you gain life, you may put that many +1/+1 counters on each creature you control. Do this only once each turn.

Dazzling Angel

Flying
Whenever another creature you control enters, you gain 1 life.

Xenk, Paladin Unbroken

Double strike
Auras you control have exalted. (Whenever a creature you control attacks alone, it gets +1/+1 until end of turn for each instance of exalted among permanents you control.)

Spirit Mantle

Enchant creature
Enchanted creature gets +1/+1 and has protection from creatures.

Psemilla, Meletian Poet

Whenever you cast your first enchantment spell each turn, create a 2/2 white Nymph enchantment creature token.
At the beginning of each combat, if you control five or more enchantments, Psemilla, Meletian Poet gets +4/+4 and gains lifelink until end of turn. (Damage dealt by this creature also causes you to gain that much life.)

Armored Ascension

Enchant creature
Enchanted creature gets +1/+1 for each Plains you control and has flying.

Archon of Sun's Grace

Flying
Lifelink (Damage dealt by this creature also causes you to gain that much life.)
Pegasus creatures you control have lifelink.
Constellation — Whenever an enchantment you control enters, create a 2/2 white Pegasus creature token with flying.

Ghostly Dancers

Flying
When Ghostly Dancers enters, return an enchantment card from your graveyard to your hand or unlock a locked door of a Room you control.
Eerie — Whenever an enchantment you control enters and whenever you fully unlock a Room, create a 3/1 white Spirit creature token with flying.

All That Glitters

Enchant creature
Enchanted creature gets +1/+1 for each artifact and/or enchantment you control.

Mantle of Leadership

Flash (You may cast this spell any time you could cast an instant.)
Enchant creature
Whenever a creature enters, enchanted creature gets +2/+2 until end of turn.

Twinblade Blessing

Flash (You may cast this spell any time you could cast an instant.)
Enchant creature
Enchanted creature has double strike. (It deals both first-strike and regular combat damage.)

Codsworth, Handy Helper

Commanders you control have ward {2}.
{T}: Add {W}{W}. Spend this mana only to cast Aura and/or Equipment spells.
{T}: Attach target Aura or Equipment you control to target creature you control. Activate only as a sorcery.

Sage's Reverie

Enchant creature
When Sage's Reverie enters, draw a card for each Aura you control that's attached to a creature.
Enchanted creature gets +1/+1 for each Aura you control that's attached to a creature.

Hyena Umbra

Enchant creature
Enchanted creature gets +1/+1 and has first strike.
Umbra armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)