Ambitious Assault

Creatures you control get +2/+0 until end of turn. If you control a modified creature, draw a card. (Equipment, Auras you control, and counters are modifications.)

Foundry Street Denizen

Whenever another red creature you control enters, Foundry Street Denizen gets +1/+0 until end of turn.

Mortician Beetle

Whenever a player sacrifices a creature, you may put a +1/+1 counter on Mortician Beetle.

Rites of Initiation

Discard any number of cards at random. Creatures you control get +1/+0 until end of turn for each card discarded this way.

Introduction to Prophecy

Mountain

Introduction to Annihilation

Exile target nonland permanent. Its controller draws a card.

Expanded Anatomy

Put two +1/+1 counters on target creature. It gains vigilance until end of turn.

Ornithopter

Body Dropper

Whenever you sacrifice another creature, put a +1/+1 counter on Body Dropper.
{B}{R}, Sacrifice another creature: Body Dropper gains menace until end of turn. (It can't be blocked except by two or more creatures.)

Kobolds of Kher Keep

Nantuko Husk

Sacrifice a creature: Nantuko Husk gets +2/+2 until end of turn.

Carrion Feeder

Carrion Feeder can't block.
Sacrifice a creature: Put a +1/+1 counter on Carrion Feeder.

Fling

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

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Reckless Impulse

Exile the top two cards of your library. Until the end of your next turn, you may play those cards.

Crookshank Kobolds

Reckless Abandon

As an additional cost to cast this spell, sacrifice a creature.
Reckless Abandon deals 4 damage to any target.

Kobold Taskmaster

Other Kobold creatures you control get +1/+0.

Goblin Bushwhacker

Kicker {R} (You may pay an additional {R} as you cast this spell.)
When this creature enters, if it was kicked, creatures you control get +1/+0 and gain haste until end of turn.

Betrothed of Fire

Enchant creature
Sacrifice an untapped creature: Enchanted creature gets +2/+0 until end of turn.
Sacrifice enchanted creature: Creatures you control get +2/+0 until end of turn.

First Day of Class

Whenever a creature you control enters this turn, put a +1/+1 counter on it and it gains haste until end of turn.
Learn. (You may reveal a Lesson card you own from outside the game and put it into your hand, or discard a card to draw a card.)

Crimson Kobolds

Bloodthrone Vampire

Sacrifice a creature: Bloodthrone Vampire gets +2/+2 until end of turn.

Teetering Peaks

Teetering Peaks enters tapped.
When Teetering Peaks enters, target creature gets +2/+0 until end of turn.
{T}: Add {R}.

Bogardan Dragonheart

Sacrifice another creature: Until end of turn, Bogardan Dragonheart becomes a Dragon with base power and toughness 4/4, flying, and haste.

Impact Tremors

Whenever a creature you control enters, this enchantment deals 1 damage to each opponent.

Bone Shards

As an additional cost to cast this spell, sacrifice a creature or discard a card.
Destroy target creature or planeswalker.