Grim Guardian

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

Riptide Chimera

Flying
At the beginning of your upkeep, return an enchantment you control to its owner's hand.

Thoughtrender Lamia

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

Panharmonicon

If an artifact or creature entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Cyclops of Eternal Fury

Thassa's Devourer

Constellation — Whenever this creature or another enchantment you control enters, target player mills two cards.

Swamp

Flameshadow Conjuring

Whenever a nontoken creature you control enters, you may pay {R}. If you do, create a token that's a copy of that creature. That token gains haste. Exile it at the beginning of the next end step.

Archetype of Aggression

Creatures you control have trample.
Creatures your opponents control lose trample and can't have or gain trample.

Akoum Refuge

This land enters tapped.
When this land enters, you gain 1 life.
{T}: Add {B} or {R}.

Spiteful Returned

Bestow {3}{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.)
Whenever this creature or enchanted creature attacks, defending player loses 2 life.
Enchanted creature gets +1/+1.

Agent of Erebos

Constellation — Whenever this creature or another enchantment you control enters, exile target player's graveyard.

Swiftwater Cliffs

This land enters tapped.
When this land enters, you gain 1 life.
{T}: Add {U} or {R}.

Spearpoint Oread

Bestow {5}{R} (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.)
First strike
Enchanted creature gets +2/+2 and has first strike.

Forgeborn Oreads

Constellation — Whenever this creature or another enchantment you control enters, this creature deals 1 damage to any target.

Archetype of Imagination

Creatures you control have flying.
Creatures your opponents control lose flying and can't have or gain flying.

Dismal Backwater

This land enters tapped.
When this land enters, you gain 1 life.
{T}: Add {U} or {B}.