Valor in Akros

Whenever a creature you control enters, creatures you control get +1/+1 until end of turn.

Goremand

As an additional cost to cast this spell, sacrifice a creature.
Flying
Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
When this creature enters, each opponent sacrifices a creature.

Rambunctious Mutt

When this creature enters, destroy target artifact or enchantment an opponent controls.

Mountain

Cathartic Reunion

As an additional cost to cast this spell, discard two cards.
Draw three cards.

Orzhov Guildgate

This land enters tapped.
{T}: Add {W} or {B}.

Gorging Vulture

Flying
When this creature enters, mill four cards. You gain 1 life for each creature card milled this way. (To mill four cards, put the top four cards of your library into your graveyard.)

Swamp

Plains

Cataclysmic Gearhulk

Vigilance
When this creature enters, each player chooses an artifact, a creature, an enchantment, and a planeswalker from among the nonland permanents they control, then sacrifices the rest.

Alpine Guide

When this creature enters, you may search your library for a Mountain card, put that card onto the battlefield tapped, then shuffle.
This creature attacks each combat if able.
When this creature leaves the battlefield, sacrifice a Mountain.

Unburial Rites

Return target creature card from your graveyard to the battlefield.
Flashback {3}{W} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Boros Guildgate

This land enters tapped.
{T}: Add {R} or {W}.

Flametongue Kavu

When this creature enters, it deals 4 damage to target creature.

Auramancer

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

Rakdos Guildgate

This land enters tapped.
{T}: Add {B} or {R}.

Rix Maadi Reveler

Spectacle {2}{B}{R} (You may cast this spell for its spectacle cost rather than its mana cost if an opponent lost life this turn.)
When this creature enters, discard a card, then draw a card. If this creature's spectacle cost was paid, instead discard your hand, then draw three cards.

Banisher Priest

When this creature enters, exile target creature an opponent controls until this creature leaves the battlefield.

Urbis Protector

When this creature enters, create a 4/4 white Angel creature token with flying.

Offspring's Revenge

At the beginning of combat on your turn, exile target red, white, or black creature card from your graveyard. Create a token that's a copy of that card, except it's 1/1. It gains haste until your next turn.

Venomous Hierophant

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
When this creature enters, mill three cards. (Put the top three cards of your library into your graveyard.)

Noosegraf Mob

This creature enters with five +1/+1 counters on it.
Whenever a player casts a spell, remove a +1/+1 counter from this creature. If you do, create a 2/2 black Zombie creature token.