Urbis Protector

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

Rootborn Defenses

Populate. Creatures you control gain indestructible until end of turn. (To populate, create a token that's a copy of a creature token you control.)

Keening Apparition

Sacrifice Keening Apparition: Destroy target enchantment.

Demolish

Taste for Mayhem

Enchant creature
Enchanted creature gets +2/+0.
Hellbent — Enchanted creature gets an additional +2/+0 as long as you have no cards in hand.

Plains

Fresh-Faced Recruit

During your turn, Fresh-Faced Recruit has first strike.

Lightning Helix

Lightning Helix deals 3 damage to any target and you gain 3 life.

Burning-Tree Vandal

Riot (This creature enters with your choice of a +1/+1 counter or haste.)
Whenever Burning-Tree Vandal attacks, you may discard a card. If you do, draw a card.

Syndicate Messenger

Flying
Afterlife 1 (When this creature dies, create a 1/1 white and black Spirit creature token with flying.)

Rising Populace

Whenever another creature or planeswalker you control dies, put a +1/+1 counter on Rising Populace.

Siege of Towers

Replicate {1}{R} (When you cast this spell, copy it for each time you paid its replicate cost. You may choose new targets for the copies.)
Target Mountain becomes a 3/1 creature. It's still a land.

Tin Street Dodger

Haste
{R}: Tin Street Dodger can't be blocked this turn except by creatures with defender.

Arrester's Zeal

Target creature gets +2/+2 until end of turn.
Addendum — If you cast this spell during your main phase, that creature gains flying until end of turn.

Aurelia, Exemplar of Justice

Flying
Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
At the beginning of combat on your turn, choose up to one target creature you control. Until end of turn, that creature gets +2/+0, gains trample if it's red, and gains vigilance if it's white.

Mountain

Stalking Vengeance

Haste
Whenever another creature you control dies, it deals damage equal to its power to target player or planeswalker.

Azorius Arrester

When Azorius Arrester enters, detain target creature an opponent controls. (Until your next turn, that creature can't attack or block and its activated abilities can't be activated.)

Scorched Rusalka

{R}, Sacrifice a creature: Scorched Rusalka deals 1 damage to target player or planeswalker.

Krenko's Command

Create two 1/1 red Goblin creature tokens.

Burning Prophet

Whenever you cast a noncreature spell, Burning Prophet gets +1/+0 until end of turn, then scry 1.