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.

Celestial Archon

Bestow {5}{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.)
Flying, first strike
Enchanted creature gets +4/+4 and has flying and first strike.

Arna Kennerüd, Skycaptain

Flying, lifelink
Ward—Discard a card.
Whenever a modified creature you control attacks, double the number of each kind of counter on it. Then for each nontoken permanent attached to it, create a token that's a copy of that permanent attached to that creature.

Starfield Mystic

Enchantment spells you cast cost {1} less to cast.
Whenever an enchantment you control is put into a graveyard from the battlefield, put a +1/+1 counter on Starfield Mystic.

Nimbus Naiad

Bestow {4}{U} (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.)
Flying
Enchanted creature gets +2/+2 and has flying.

Nyxborn Triton

Bestow {4}{U} (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.)
Enchanted creature gets +2/+3.

Glyph Elemental

Bestow {1}{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.)
Landfall — Whenever a land you control enters, put a +1/+1 counter on Glyph Elemental.
Enchanted creature gets +1/+1 for each +1/+1 counter on Glyph Elemental.

Nighthowler

Bestow {2}{B}{B} (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.)
Nighthowler and enchanted creature each get +X/+X, where X is the number of creature cards in all graveyards.

Hopeful Eidolon

Bestow {3}{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.)
Lifelink (Damage dealt by this creature also causes you to gain that much life.)
Enchanted creature gets +1/+1 and has lifelink.

Starnheim Courser

Flying
Artifact and enchantment spells you cast cost {1} less to cast.

Pearl-Ear, Imperial Advisor

Lifelink
Enchantment spells you cast have affinity for Auras. (They cost {1} less to cast for each Aura you control.)
Whenever you cast an Aura spell that targets a modified permanent you control, draw a card. (Equipment, Auras you control, and counters are modifications.)

Indebted Spirit

Bestow {2}{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.)
Afterlife 1 (When this permanent is put into a graveyard from the battlefield, create a 1/1 white and black Spirit creature token with flying.)
Enchanted creature gets +1/+1 and has afterlife 1.

Cavern Lampad

Bestow {5}{B} (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.)
Intimidate (This creature can't be blocked except by artifact creatures and/or creatures that share a color with it.)
Enchanted creature gets +2/+2 and has intimidate.