Sai of the Shinobi

Equipped creature gets +1/+1.
Whenever a creature you control enters, you may attach Sai of the Shinobi to it.
Equip {2}

Ring of Valkas

Equipped creature has haste. (It can attack and {T} no matter when it came under your control.)
At the beginning of your upkeep, put a +1/+1 counter on equipped creature if it's red.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Honed Khopesh

Equipped creature gets +1/+1.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Rograkh, Son of Rohgahh

First strike, menace, trample
Partner (You can have two commanders if both have partner.)

Mask of Avacyn

Equipped creature gets +1/+2 and has hexproof. (It can't be the target of spells or abilities your opponents control.)
Equip {3}

Undying Rage

Enchant creature
Enchanted creature gets +2/+2 and can't block.
When Undying Rage is put into a graveyard from the battlefield, return Undying Rage to its owner's hand.

Blood Mist

At the beginning of combat on your turn, target creature you control gains double strike until end of turn.

Sol Ring

Jeska, Thrice Reborn

Jeska, Thrice Reborn enters with a loyalty counter on her for each time you've cast a commander from the command zone this game.
0: Choose target creature. Until your next turn, if that creature would deal combat damage to one of your opponents, it deals triple that damage to that player instead.
−X: Jeska, Thrice Reborn deals X damage to each of up to three targets.
Jeska, Thrice Reborn can be your commander.
Partner

Short Sword

Stormrider Rig

Equipped creature gets +1/+1.
Whenever a creature you control enters, you may attach Stormrider Rig to it.
Equip {2}

Leonin Scimitar

Fiery Mantle

Enchant creature
{R}: Enchanted creature gets +1/+0 until end of turn.
When Fiery Mantle is put into a graveyard from the battlefield, return Fiery Mantle to its owner's hand.

Endless Atlas

{2}, {T}: Draw a card. Activate only if you control three or more lands with the same name.

Bone Saw

Equipped creature gets +1/+0.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Prying Blade

Equipped creature gets +1/+0.
Whenever equipped creature deals combat damage to a player, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Fires of Invention

You can cast spells only during your turn and you can cast no more than two spells each turn.
You may cast spells with mana value less than or equal to the number of lands you control without paying their mana costs.

Dictate of the Twin Gods

Flash
If a source would deal damage to a permanent or player, it deals double that damage to that permanent or player instead.

Bonesplitter

Wings of Hubris

Equipped creature has flying.
Sacrifice Wings of Hubris: Equipped creature can't be blocked this turn. Sacrifice it at the beginning of the next end step.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Inspiring Statuary

Nonartifact spells you cast have improvise. (Your artifacts can help cast those spells. Each artifact you tap after you're done activating mana abilities pays for {1}.)

Underworld Breach

Each nonland card in your graveyard has escape. The escape cost is equal to the card's mana cost plus exile three other cards from your graveyard. (You may cast cards from your graveyard for their escape cost.)
At the beginning of the end step, sacrifice Underworld Breach.

Saheeli's Directive

Improvise (Each artifact you tap after you're done activating mana abilities pays for {1}.)
Reveal the top X cards of your library. You may put any number of artifact cards with mana value X or less from among them onto the battlefield. Then put all cards revealed this way that weren't put onto the battlefield into your graveyard.

Golem-Skin Gauntlets

Equipped creature gets +1/+0 for each Equipment attached to it.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery. This card enters unattached and stays on the battlefield if the creature leaves.)

Prowler's Helm

Equipped creature can't be blocked except by Walls.
Equip {2}

Experimental Frenzy

You may look at the top card of your library any time.
You may play lands and cast spells from the top of your library.
You can't play lands or cast spells from your hand.
{3}{R}: Destroy Experimental Frenzy.

The Brute

Enchant creature
Enchanted creature gets +1/+0.
{R}{R}{R}: Regenerate enchanted creature.

Magus of the Wheel

{1}{R}, {T}, Sacrifice Magus of the Wheel: Each player discards their hand, then draws seven cards.

Valakut Exploration

Landfall — Whenever a land you control enters, exile the top card of your library. You may play that card for as long as it remains exiled.
At the beginning of your end step, if there are cards exiled with Valakut Exploration, put them into their owner's graveyard, then Valakut Exploration deals that much damage to each opponent.