Barrensteppe Siege

As this enchantment enters, choose Abzan or Mardu.
• Abzan — At the beginning of your end step, put a +1/+1 counter on each creature you control.
• Mardu — At the beginning of your end step, if a creature died under your control this turn, each opponent sacrifices a creature of their choice.

Betor, Kin to All

Flying
At the beginning of your end step, if creatures you control have total toughness 10 or greater, draw a card. Then if creatures you control have total toughness 20 or greater, untap each creature you control. Then if creatures you control have total toughness 40 or greater, each opponent loses half their life, rounded up.

Bone-Cairn Butcher

Warrior

Mobilize 2 (Whenever this creature attacks, create two tapped and attacking 1/1 red Warrior creature tokens. Sacrifice them at the beginning of the next end step.)
Attacking tokens you control have deathtouch.

Call the Spirit Dragons

Dragons you control have indestructible.
At the beginning of your upkeep, for each color, put a +1/+1 counter on a Dragon you control of that color. If you put +1/+1 counters on five Dragons this way, you win the game.

Cori Mountain Stalwart

Flurry — Whenever you cast your second spell each turn, this creature deals 2 damage to each opponent and you gain 2 life.

Death Begets Life

Destroy all creatures and enchantments. Draw a card for each permanent destroyed this way.

Defibrillating Current

Defibrillating Current deals 4 damage to target creature or planeswalker and you gain 2 life.

Disruptive Stormbrood

Flying
When this creature enters, destroy up to one target artifact or enchantment.

Petty Revenge

Destroy target creature with power 3 or less. (Then shuffle this card into its owner's library.)

Disruptive Stormbrood // Petty Revenge

Dragonback Assault

Dragon

When this enchantment enters, it deals 3 damage to each creature and each planeswalker.
Landfall — Whenever a land you control enters, create a 4/4 red Dragon creature token with flying.

Poised Practitioner

Flurry — Whenever you cast your second spell each turn, put a +1/+1 counter on this creature. Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Dragonclaw Strike

Double the power and toughness of target creature you control until end of turn. Then it fights up to one target creature an opponent controls. (Each deals damage equal to its power to the other.)

Effortless Master

Vigilance
Menace (This creature can't be blocked except by two or more creatures.)
This creature enters with two +1/+1 counters on it if you've cast two or more spells this turn.

Eshki Dragonclaw

Vigilance, trample, ward {1}
At the beginning of combat on your turn, if you've cast both a creature spell and a noncreature spell this turn, draw a card and put two +1/+1 counters on Eshki Dragonclaw.

Fangkeeper's Familiar

Flash
When this creature enters, choose one —
• You gain 3 life and surveil 3. (Look at the top three cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)
• Destroy target enchantment.
• Counter target creature spell.

Felothar, Dawn of the Abzan

Trample
Whenever Felothar enters or attacks, you may sacrifice a nonland permanent. When you do, put a +1/+1 counter on each creature you control.

Flamehold Grappler

First strike
When this creature enters, copy the next spell you cast this turn when you cast it. You may choose new targets for the copy. (A copy of a permanent spell becomes a token.)

Tarkir: Dragonstorm