Heliod's Emissary

Bestow {6}{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.)
Whenever Heliod's Emissary or enchanted creature attacks, tap target creature an opponent controls.
Enchanted creature gets +3/+3.

Observant Alseid

Bestow {4}{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.)
Vigilance
Enchanted creature gets +2/+2 and has vigilance.

Thassa's Emissary

Bestow {5}{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.)
Whenever Thassa's Emissary or enchanted creature deals combat damage to a player, draw a card.
Enchanted creature gets +3/+3.

Battlewise Hoplite

Heroic — Whenever you cast a spell that targets Battlewise Hoplite, put a +1/+1 counter on Battlewise Hoplite, then scry 1. (To scry 1, look at the top card of your library, then you may put that card on the bottom.)

Revoke Existence

War-Wing Siren

Flying
Heroic — Whenever you cast a spell that targets War-Wing Siren, put a +1/+1 counter on War-Wing Siren.

Triton Fortune Hunter

Heroic — Whenever you cast a spell that targets Triton Fortune Hunter, draw a card.

Island

Ephara's Enlightenment

Enchant creature
When Ephara's Enlightenment enters, put a +1/+1 counter on enchanted creature.
Enchanted creature has flying.
Whenever a creature you control enters, you may return Ephara's Enlightenment to its owner's hand.

Nyxborn Shieldmate

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 to a creature.)
Enchanted creature gets +1/+2.

Wavecrash Triton

Heroic — Whenever you cast a spell that targets Wavecrash Triton, tap target creature an opponent controls. That creature doesn't untap during its controller's next untap step.

Excoriate

Meletis Astronomer

Heroic — Whenever you cast a spell that targets Meletis Astronomer, look at the top three cards of your library. You may reveal an enchantment card from among them and put it into your hand. Put the rest on the bottom of your library in any order.

Ghostblade Eidolon

Bestow {5}{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.)
Double strike (This creature deals both first-strike and regular combat damage.)
Enchanted creature gets +1/+1 and has double strike.