Fear of Impostors

Flash
When Fear of Impostors enters, counter target spell. Its controller manifests dread. (That player looks at the top two cards of their library, then puts one onto the battlefield face down as a 2/2 creature and the other into their graveyard. If it's a creature card, it can be turned face up any time for its mana cost.)

Doomwake Giant

Constellation — Whenever Doomwake Giant or another enchantment you control enters, creatures your opponents control get -1/-1 until end of turn.

Fate Unraveler

Whenever an opponent draws a card, Fate Unraveler deals 1 damage to that player.

Penance

Put a card from your hand on top of your library: The next time a black or red source of your choice would deal damage this turn, prevent that damage.

Blind Obedience

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)
Artifacts and creatures your opponents control enter tapped.

Negate

Grim Guardian

Constellation — Whenever Grim Guardian or another enchantment you control enters, each opponent loses 1 life.

Dovin's Veto

This spell can't be countered.
Counter target noncreature spell.

Callaphe, Beloved of the Sea

Callaphe's power is equal to your devotion to blue. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)
Creatures and enchantments you control have "Spells your opponents cast that target this permanent cost {1} more to cast."

Sphere of Safety

Creatures can't attack you or planeswalkers you control unless their controller pays {X} for each of those creatures, where X is the number of enchantments you control.

Propaganda

Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.

Hall of Heliod's Generosity

{T}: Add {C}.
{1}{W}, {T}: Put target enchantment card from your graveyard on top of your library.

Counterspell

Ondu Spiritdancer

Whenever an enchantment you control enters, you may create a token that's a copy of it. Do this only once each turn.

Arvinox, the Mind Flail

Arvinox, the Mind Flail isn't a creature unless you control three or more permanents you don't own.
At the beginning of your end step, exile the bottom card of each opponent's library face down. For as long as those cards remain exiled, you may look at them, you may cast permanent spells from among them, and you may spend mana as though it were mana of any color to cast those spells.

Cacophony Unleashed

When Cacophony Unleashed enters, if you cast it, destroy all nonenchantment creatures.
Whenever Cacophony Unleashed or another enchantment you control enters, until end of turn, Cacophony Unleashed becomes a legendary 6/6 Nightmare God creature with menace and deathtouch. It's still an enchantment.

Demon of Fate's Design

Flying, trample
Once during each of your turns, you may cast an enchantment spell by paying life equal to its mana value rather than paying its mana cost.
{2}{B}, Sacrifice another enchantment: Demon of Fate's Design gets +X/+0 until end of turn, where X is the sacrificed enchantment's mana value.

Heliod, the Warped Eclipse

You may cast spells as though they had flash.
Spells you cast cost {1} less to cast for each card your opponents have drawn this turn.

Heliod, the Radiant Dawn

When Heliod, the Radiant Dawn enters, return target enchantment card that isn't a God from your graveyard to your hand.
{3}{U/P}: Transform Heliod, the Radiant Dawn. Activate only as a sorcery. ({U/P} can be paid with either {U} or 2 life.)

Heliod, the Radiant Dawn // Heliod, the Warped Eclipse

Imprisoned in the Moon

Enchant creature, land, or planeswalker
Enchanted permanent is a colorless land with "{T}: Add {C}" and loses all other card types and abilities.

Fierce Guardianship

If you control a commander, you may cast this spell without paying its mana cost.
Counter target noncreature spell.

Deadly Rollick

If you control a commander, you may cast this spell without paying its mana cost.
Exile target creature.

Starnheim Courser

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

Moon-Blessed Cleric

Divine Intervention — When Moon-Blessed Cleric enters, you may search your library for an enchantment card, reveal it, then shuffle and put that card on top.

Aminatou, Veil Piercer

At the beginning of your upkeep, surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)
Each enchantment card in your hand has miracle. Its miracle cost is equal to its mana cost reduced by {4}. (You may cast a card for its miracle cost when you draw it if it's the first card you drew this turn.)

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.

Mesa Enchantress

Whenever you cast an enchantment spell, you may draw a card.

Mirrormade

You may have Mirrormade enter as a copy of any artifact or enchantment on the battlefield.

Ephara, Ever-Sheltering

Ephara, Ever-Sheltering has lifelink and indestructible as long as you control at least three other enchantments.
Whenever another enchantment you control enters, draw a card.

Invasion of Theros

(As a Siege enters, choose an opponent to protect it. You and others can attack it. When it's defeated, exile it, then cast it transformed.)
When Invasion of Theros enters, search your library for an Aura, God, or Demigod card, reveal it, put it into your hand, then shuffle.

Invasion of Theros // Ephara, Ever-Sheltering

Shark Typhoon

Whenever you cast a noncreature spell, create an X/X blue Shark creature token with flying, where X is that spell's mana value.
Cycling {X}{1}{U} ({X}{1}{U}, Discard this card: Draw a card.)
When you cycle Shark Typhoon, create an X/X blue Shark creature token with flying.

Underworld Coinsmith

Constellation — Whenever Underworld Coinsmith or another enchantment you control enters, you gain 1 life.
{W}{B}, Pay 1 life: Each opponent loses 1 life.

Estrid's Invocation

You may have Estrid's Invocation enter as a copy of an enchantment you control, except it has "At the beginning of your upkeep, you may exile this enchantment. If you do, return it to the battlefield under its owner's control."

Zur, Eternal Schemer

Flying
Enchantment creatures you control have deathtouch, lifelink, and hexproof.
{1}{W}: Target non-Aura enchantment you control becomes a creature in addition to its other types and has base power and base toughness each equal to its mana value.

Thoughtrender Lamia

Constellation — Whenever Thoughtrender Lamia or another enchantment you control enters, each opponent discards a card.

Thassa, God of the Sea

Indestructible
As long as your devotion to blue is less than five, Thassa isn't a creature. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)
At the beginning of your upkeep, scry 1.
{1}{U}: Target creature you control can't be blocked this turn.

Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

Alela, Artful Provocateur

Flying, deathtouch, lifelink
Other creatures you control with flying get +1/+0.
Whenever you cast an artifact or enchantment spell, create a 1/1 blue Faerie creature token with flying.

Ghostly Prison

Arcane Denial

Counter target spell. Its controller may draw up to two cards at the beginning of the next turn's upkeep.
You draw a card at the beginning of the next turn's upkeep.

Perplexing Chimera

Whenever an opponent casts a spell, you may exchange control of Perplexing Chimera and that spell. If you do, you may choose new targets for the spell. (If the spell becomes a permanent, you control that permanent.)

Teferi's Protection

Until your next turn, your life total can't change and you gain protection from everything. All permanents you control phase out. (While they're phased out, they're treated as though they don't exist. They phase in before you untap during your untap step.)
Exile Teferi's Protection.

Inquisitive Glimmer

Enchantment spells you cast cost {1} less to cast.
Unlock costs you pay cost {1} less.