Curious Obsession

Enchant creature
Enchanted creature gets +1/+1 and has "Whenever this creature deals combat damage to a player, you may draw a card."
At the beginning of your end step, if you didn't attack with a creature this turn, sacrifice Curious Obsession.

Overrun

Creatures you control get +3/+3 and gain trample until end of turn. (Each of those creatures can deal excess combat damage to the player or planeswalker it's attacking.)

Windstorm Drake

Flying
Other creatures you control with flying get +1/+0.

Unsubstantiate

Return target spell or creature to its owner's hand.

Blue Dragon

Flying
Lightning Breath — When Blue Dragon enters, until your next turn, target creature an opponent controls gets -3/-0, up to one other target creature gets -2/-0, and up to one other target creature gets -1/-0.

Thud

As an additional cost to cast this spell, sacrifice a creature.
Thud deals damage equal to the sacrificed creature's power to any target.

Swamp

Cloudkin Seer

Flying
When Cloudkin Seer enters, draw a card.

Defile

Target creature gets -1/-1 until end of turn for each Swamp you control.

Wanted Scoundrels

When Wanted Scoundrels dies, target opponent creates two Treasure tokens. (They're artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")

Thermo-Alchemist

Defender
{T}: Thermo-Alchemist deals 1 damage to each opponent.
Whenever you cast an instant or sorcery spell, untap Thermo-Alchemist.

Black Dragon

Flying
Acid Breath — When Black Dragon enters, target creature an opponent controls gets -3/-3 until end of turn.

Winged Words

This spell costs {1} less to cast if you control a creature with flying.
Draw two cards.

Bestial Menace

Create a 1/1 green Snake creature token, a 2/2 green Wolf creature token, and a 3/3 green Elephant creature token.

Reassembling Skeleton

{1}{B}: Return this card from your graveyard to the battlefield tapped.

Elephant Guide

Enchant creature
Enchanted creature gets +3/+3.
When enchanted creature dies, create a 3/3 green Elephant creature token.

Guttersnipe

Whenever you cast an instant or sorcery spell, this creature deals 2 damage to each opponent.

Goblin Gathering

Create a number of 1/1 red Goblin creature tokens equal to two plus the number of cards named Goblin Gathering in your graveyard.

Tendrils of Corruption

Tendrils of Corruption deals X damage to target creature and you gain X life, where X is the number of Swamps you control.

Growth Cycle

Target creature gets +3/+3 until end of turn. It gets an additional +2/+2 until end of turn for each card named Growth Cycle in your graveyard.

Lifelink

Enchant creature
Enchanted creature has lifelink. (Damage dealt by the creature also causes its controller to gain that much life.)

Flame Lash

Sign in Blood

Target player draws two cards and loses 2 life.

Forest

Metropolis Sprite

Flying
{U}: Metropolis Sprite gets +1/-1 until end of turn.

Auramancer

When Auramancer enters, you may return target enchantment card from your graveyard to your hand.

Armored Ascension

Enchant creature
Enchanted creature gets +1/+1 for each Plains you control and has flying.

Lofty Denial

Counter target spell unless its controller pays {1}. If you control a creature with flying, counter that spell unless its controller pays {4} instead.

Plains

Militia Bugler

Vigilance (Attacking doesn't cause this creature to tap.)
When Militia Bugler enters, look at the top four cards of your library. You may reveal a creature card with power 2 or less from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

Young Pyromancer

Whenever you cast an instant or sorcery spell, create a 1/1 red Elemental creature token.

Green Dragon

Flying
Poison Breath — When Green Dragon enters, until end of turn, whenever a creature an opponent controls is dealt damage, destroy it.

Mountain

Talrand's Invocation

Create two 2/2 blue Drake creature tokens with flying.

Faerie Miscreant

Flying
When Faerie Miscreant enters, if you control another creature named Faerie Miscreant, draw a card.

Vampire Sovereign

Flying
When Vampire Sovereign enters, target opponent loses 3 life and you gain 3 life.

Valorous Stance

Choose one —
• Target creature gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)
• Destroy target creature with toughness 4 or greater.

Lightning Strike

Lightning Strike deals 3 damage to any target.

Red Dragon

Flying
Fire Breath — When Red Dragon enters, it deals 4 damage to each opponent.

Searing Spear

Searing Spear deals 3 damage to any target.

Master Symmetrist

Reach
Whenever a creature you control with power equal to its toughness attacks, it gains trample until end of turn.

Jade Mage

{2}{G}: Create a 1/1 green Saproling creature token.

Act of Treason

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn. (It can attack and {T} this turn.)

Skyblade's Boon

Enchant creature
Enchanted creature gets +1/+1 and has flying.
{2}{W}: Return Skyblade's Boon to its owner's hand. Activate only if Skyblade's Boon is on the battlefield or in your graveyard.

Rabid Bite

Target creature you control deals damage equal to its power to target creature you don't control.

Llanowar Elves

Llanowar Visionary

When Llanowar Visionary enters, draw a card.
{T}: Add {G}.

Elvish Mystic

Village Rites

As an additional cost to cast this spell, sacrifice a creature.
Draw two cards.

Liliana's Shade

When Liliana's Shade enters, you may search your library for a Swamp card, reveal it, put it into your hand, then shuffle.
{B}: Liliana's Shade gets +1/+1 until end of turn.

Flutterfox

As long as you control an artifact or enchantment, Flutterfox has flying.

Frogify

Enchant creature
Enchanted creature loses all abilities and is a blue Frog creature with base power and toughness 1/1. (It loses all other card types and creature types.)

Favorable Winds

Creatures you control with flying get +1/+1.

Acidic Slime

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
When Acidic Slime enters, destroy target artifact, enchantment, or land.

Youthful Knight

Heliod's Pilgrim

When Heliod's Pilgrim enters, you may search your library for an Aura card, reveal it, put it into your hand, then shuffle.

Arrest

Enchant creature
Enchanted creature can't attack or block, and its activated abilities can't be activated.

Island

Dusk Legion Zealot

When Dusk Legion Zealot enters, you draw a card and you lose 1 life.

Bonds of Faith

Enchant creature
Enchanted creature gets +2/+2 as long as it's a Human. Otherwise, it can't attack or block.

Steadfast Guard

Vigilance (Attacking doesn't cause this creature to tap.)

White Dragon

Flying
Cold Breath — When White Dragon enters, tap target creature an opponent controls. That creature doesn't untap during its controller's next untap step.