Concerted Effort

At the beginning of each upkeep, creatures you control gain flying until end of turn if a creature you control has flying. The same is true for fear, first strike, double strike, landwalk, protection, trample, and vigilance.

Jenny, Generated Anomaly

Double strike
Whenever Jenny deals combat damage to a player, it explores. (Reveal the top card of your library. Put that card into your hand if it's a land. Otherwise, put a +1/+1 counter on this creature, then put the card back or put it into your graveyard.)

Sunhome Guildmage

{1}{R}{W}: Creatures you control get +1/+0 until end of turn.
{2}{R}{W}: Create a 1/1 red and white Soldier creature token with haste.

Iroas's Champion

Double strike (This creature deals both first-strike and regular combat damage.)

Prophetic Flamespeaker

Double strike, trample
Whenever Prophetic Flamespeaker deals combat damage to a player, exile the top card of your library. You may play it this turn.

Phyrexian Dragon Engine

Double strike
When Phyrexian Dragon Engine enters from your graveyard, you may discard your hand. If you do, draw three cards.
Unearth {3}{R}{R}
(Melds with Mishra, Claimed by Gix.)

Mirran Crusader

Double strike, protection from black and from green

Akroma's Will

Choose one. If you control a commander as you cast this spell, you may choose both instead.
• Creatures you control gain flying, vigilance, and double strike until end of turn.
• Creatures you control gain lifelink, indestructible, and protection from each color until end of turn.

Birthright Boon

Search your library for an Aura or Equipment card, reveal it, put it into your hand, then shuffle.

Kellan, the Fae-Blooded

Double strike
Other creatures you control get +1/+0 for each Aura and Equipment attached to Kellan, the Fae-Blooded.

Kellan, the Fae-Blooded // Birthright Boon

Swiftblade Vindicator

Kor Duelist

As long as Kor Duelist is equipped, it has double strike. (It deals both first-strike and regular combat damage.)

Boros Swiftblade

Moria Marauder

Double strike
Whenever a Goblin or Orc you control deals combat damage to a player, exile the top card of your library. You may play that card this turn.

Apostle of Purifying Light

Protection from black (This creature can't be blocked, targeted, dealt damage, enchanted, or equipped by anything black.)
{2}: Exile target card from a graveyard.

Skyhunter Skirmisher

Illuminator Virtuoso

Double strike
Whenever Illuminator Virtuoso becomes the target of a spell you control, it connives. (Draw a card, then discard a card. If you discarded a nonland card, put a +1/+1 counter on this creature.)

Théoden, King of Rohan

Whenever Théoden, King of Rohan or another Human you control enters, target creature gains double strike until end of turn.

Beloved Chaplain

Kor Blademaster

Double strike
Equipped Warriors you control have double strike.

Lizard Blades

Double strike
Equipped creature has double strike.
Reconfigure {2} ({2}: Attach to target creature you control; or unattach from a creature. Reconfigure only as a sorcery. While attached, this isn't a creature.)