Spiked Pit Trap

Flash
{5}, {T}, Sacrifice Spiked Pit Trap: Choose target creature, then roll a d20.
1—9 | Spiked Pit Trap deals 5 damage to that creature.
10—20 | Spiked Pit Trap deals 5 damage to that creature. Create a Treasure token.

Greel's Caress

Flash
Enchant creature
Enchanted creature gets -3/-0.

Slimebind

Flash
Enchant creature
Enchanted creature gets -4/-0.

Offalsnout

Flash
When Offalsnout leaves the battlefield, exile target card from a graveyard.
Evoke {B} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters the battlefield.)

Mystic Restraints

Flash
Enchant creature
When Mystic Restraints enters the battlefield, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.

Starlit Mantle

Flash
Enchant creature you control
When Starlit Mantle enters the battlefield, enchanted creature gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)
Enchanted creature gets +1/+1.

Short Circuit

Flash
Enchant artifact or creature
As long as enchanted permanent is a creature, it gets -3/-0 and loses flying.

Scale of Chiss-Goria

Flash
Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
{T}: Target creature gets +0/+1 until end of turn.

So Tiny

Flash
Enchant creature
Enchanted creature gets -2/-0. It gets -6/-0 instead as long as its controller has seven or more cards in their graveyard.

Disturbing Conversion

Flash
Enchant creature
When Disturbing Conversion enters the battlefield, each player mills two cards.
Enchanted creature gets -X/-0, where X is the number of cards in its controller's graveyard.

Supply Drop

Flash
When Supply Drop enters the battlefield, target creature you control gets +2/+2 until end of turn.
{4}, {T}, Sacrifice Supply Drop: Draw a card.

Prismwake Merrow

Flash
When Prismwake Merrow enters the battlefield, target permanent becomes the color or colors of your choice until end of turn.

Spontaneous Mutation

Flash
Enchant creature
Enchanted creature gets -X/-0, where X is the number of cards in your graveyard.

Cunning Nightbonder

Flash
Spells with flash you cast cost {1} less to cast and can't be countered.

Bonds of Quicksilver

Flash (You may cast this spell any time you could cast an instant.)
Enchant creature
Enchanted creature doesn't untap during its controller's untap step.

Chrome Prowler

Flash
When Chrome Prowler enters the battlefield, tap target creature an opponent controls.

Masked Blackguard

Flash (You may cast this spell any time you could cast an instant.)
{2}{B}: Masked Blackguard gets +1/+1 until end of turn.

Spellstutter Sprite

Flash
Flying
When Spellstutter Sprite enters the battlefield, counter target spell with mana value X or less, where X is the number of Faeries you control.

Capture Sphere

Flash (You may cast this spell any time you could cast an instant.)
Enchant creature
When Capture Sphere enters the battlefield, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.

Cloaked Siren

Flash (You may cast this spell any time you could cast an instant.)
Flying

Maggot Therapy

Flash
Enchant creature
Enchanted creature gets +2/-2.

Manticore

Flash
Flying
Tail Spikes — When Manticore enters the battlefield, destroy target creature an opponent controls that was dealt damage this turn.

Goblin Firebomb

Flash
{7}, {T}, Sacrifice Goblin Firebomb: Destroy target permanent.

Cradle of Safety

Flash
Enchant creature you control
When Cradle of Safety enters the battlefield, enchanted creature gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)
Enchanted creature gets +1/+1.

Tooth of Chiss-Goria

Flash
Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
{T}: Target creature gets +1/+0 until end of turn.

Buoyancy

Flash
Enchant creature
Enchanted creature has flying.

Whisper Agent

Flash
When Whisper Agent enters the battlefield, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Sea Legs

Flash
Enchant creature
Enchanted creature gets +0/+2 as long as it's a Pirate. Otherwise, it gets -2/-0.

Zulaport Duelist

Flash
When Zulaport Duelist enters the battlefield, up to one target creature gets -2/-0 until end of turn. Its controller mills two cards. (They put the top two cards of their library into their graveyard.)

Vexing Gull

Baton of Courage

Flash
Sunburst (This enters the battlefield with a charge counter on it for each color of mana spent to cast it.)
Remove a charge counter from Baton of Courage: Target creature gets +1/+1 until end of turn.

Dire Mimic

Flash
{T}, Sacrifice Dire Mimic: Add one mana of any color.
{3}: Dire Mimic becomes a Shapeshifter artifact creature with base power and toughness 5/5 until end of turn.

Blessing of Leeches

Flash
Enchant creature
At the beginning of your upkeep, you lose 1 life.
{0}: Regenerate enchanted creature.

Crystacean

Quick-Draw Dagger

Flash
When Quick-Draw Dagger enters the battlefield, attach it to target creature you control. That creature gains first strike until end of turn.
Equipped creature gets +1/+1.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Aven Reedstalker

Dewdrop Spy

Flash
Flying
When Dewdrop Spy enters the battlefield, look at the top card of target player's library.

Swamp

Mists of Littjara

Flash
Enchant creature or Vehicle
Enchanted creature gets -3/-0.

Breaching Hippocamp

Flash (You may cast this spell any time you could cast an instant.)
When Breaching Hippocamp enters the battlefield, untap another target creature you control.

Saiba Cryptomancer

Flash
Backup 1 (When this creature enters the battlefield, put a +1/+1 counter on target creature. If that's another creature, it gains the following ability until end of turn.)
Hexproof

Hired Blade

Flash (You may cast this spell any time you could cast an instant.)

Crookclaw Transmuter

Flash
Flying
When Crookclaw Transmuter enters the battlefield, switch target creature's power and toughness until end of turn.

Faerie Duelist

Flash
Flying
When Faerie Duelist enters the battlefield, target creature an opponent controls gets -2/-0 until end of turn.

Omen of the Sea

Flash
When Omen of the Sea enters the battlefield, scry 2, then draw a card.
{2}{U}, Sacrifice Omen of the Sea: Scry 2.

Burrog Befuddler

Flash
When Burrog Befuddler enters the battlefield, target creature an opponent controls gets -1/-0 until end of turn.

Brinebarrow Intruder

Flash
When Brinebarrow Intruder enters the battlefield, target creature an opponent controls gets -2/-0 until end of turn.

Bladed Battle-Fan

Flash
When Bladed Battle-Fan enters the battlefield, attach it to target creature you control. That creature gains indestructible until end of turn.
Equipped creature gets +1/+0.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Leaden Fists

Flash (You may cast this spell any time you could cast an instant.)
Enchant creature
Enchanted creature gets +3/+3 and doesn't untap during its controller's untap step.

Ragged Veins

Flash
Enchant creature
Whenever enchanted creature is dealt damage, its controller loses that much life.

Springjaw Trap

Flash
{4}, {T}, Sacrifice Springjaw Trap: It deals 3 damage to any target.

Eel Umbra

Flash (You may cast this spell any time you could cast an instant.)
Enchant creature
Enchanted creature gets +1/+1.
Totem armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)

Island

Riptide Turtle

Blitz Leech

Flash
When Blitz Leech enters the battlefield, target creature an opponent controls gets -2/-2 until end of turn. Remove all counters from that creature.

Omen of the Dead

Flash
When Omen of the Dead enters the battlefield, return target creature card from your graveyard to your hand.
{2}{B}, Sacrifice Omen of the Dead: Scry 2.

Celestial Messenger

Flash (You may cast this card any time you could cast an instant.)
Flying
Celestial Messenger gets +1/+1 as long as you control a Yanling planeswalker.

Nephalia Seakite

Galvanic Key

Jarl of the Forsaken

Flash
When Jarl of the Forsaken enters the battlefield, destroy target creature or planeswalker an opponent controls that was dealt damage this turn.
Foretell {1}{B} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Alexi's Cloak

Flash
Enchant creature
Enchanted creature has shroud. (It can't be the target of spells or abilities.)

Ophidian Eye

Flash (You may cast this spell any time you could cast an instant.)
Enchant creature
Whenever enchanted creature deals damage to an opponent, you may draw a card.

Nivix Barrier

Flash (You may cast this spell any time you could cast an instant.)
Defender (This creature can't attack.)
When Nivix Barrier enters the battlefield, target attacking creature gets -4/-0 until end of turn.

Sentinels of Glen Elendra

Pestermite

Flash
Flying
When Pestermite enters the battlefield, you may tap or untap target permanent.

Lurking Deadeye

Flash
When Lurking Deadeye enters the battlefield, destroy target creature that was dealt damage this turn.

Torpor Dust

Nimana Skydancer

Flash
Flying
When Nimana Skydancer enters the battlefield, target opponent mills two cards. (They put the top two cards of their library into their graveyard.)