Three Steps Ahead

Spree (Choose one or more additional costs.)
+ {1}{U} — Counter target spell.
+ {3} — Create a token that's a copy of target artifact or creature you control.
+ {2} — Draw two cards, then discard a card.

Slumbering Keepguard

Whenever an enchantment you control enters, scry 1.
{2}{W}: This creature gets +1/+1 until end of turn for each enchantment you control.

United Battlefront

Look at the top seven cards of your library. Put up to two noncreature, nonland permanent cards with mana value 3 or less from among them onto the battlefield. Put the rest on the bottom of your library in a random order.

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."

Gift of Immortality

Enchant creature
When enchanted creature dies, return that card to the battlefield under its owner's control. Return this card to the battlefield attached to that creature at the beginning of the next end step.

Sky-Blessed Samurai

Affinity for enchantments (This spell costs {1} less to cast for each enchantment you control.)
Flying

Witness Protection

Enchant creature
Enchanted creature loses all abilities and is a green and white Citizen creature with base power and toughness 1/1 named Legitimate Businessperson. (It loses all other colors, card types, creature types, and names.)

Valgavoth's Lair

Hexproof
This land enters tapped. As it enters, choose a color.
{T}: Add one mana of the chosen color.

Temporary Lockdown

When this enchantment enters, exile each nonland permanent with mana value 2 or less until this enchantment leaves the battlefield.

Brine Giant

Affinity for enchantments (This spell costs {1} less to cast for each enchantment you control.)

Starfield of Nyx

At the beginning of your upkeep, you may return target enchantment card from your graveyard to the battlefield.
As long as you control five or more enchantments, each other non-Aura enchantment you control is a creature in addition to its other types and has base power and base toughness each equal to its mana value.

Entity Tracker

Flash
Eerie — Whenever an enchantment you control enters and whenever you fully unlock a Room, draw a card.