Birthing Ritual

At the beginning of your end step, if you control a creature, look at the top seven cards of your library. Then you may sacrifice a creature. If you do, you may put a creature card with mana value X or less from among those cards onto the battlefield, where X is 1 plus the sacrificed creature's mana value. Put the rest on the bottom of your library in a random order.

Dragonhawk, Fate's Tempest

Flying
Whenever Dragonhawk enters or attacks, exile the top X cards of your library, where X is the number of creatures you control with power 4 or greater. You may play those cards until your next end step. At the beginning of your next end step, Dragonhawk deals 2 damage to each opponent for each of those cards that are still exiled.

Quantum Riddler

Flying
When this creature enters, draw a card.
As long as you have one or fewer cards in hand, if you would draw one or more cards, you draw that many cards plus one instead.
Warp {1}{U}

Frostcliff Siege

As this enchantment enters, choose Jeskai or Temur.
• Jeskai — Whenever one or more creatures you control deal combat damage to a player, draw a card.
• Temur — Creatures you control get +1/+0 and have trample and haste.

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.

Dragonfire Blade

Equipped creature gets +2/+2 and has hexproof from monocolored.
Equip {4}. This ability costs {1} less to activate for each color of the creature it targets.