Boros Signet

Orzhov Signet

Rakdos Signet

Fist of Suns

You may pay {W}{U}{B}{R}{G} rather than pay the mana cost for spells you cast.

Pearl Medallion

White spells you cast cost {1} less to cast.

Dream Halls

Rather than pay the mana cost for a spell, its controller may discard a card that shares a color with that spell.

Rhythm of the Wild

Creature spells you control can't be countered.
Nontoken creatures you control have riot. (They enter with your choice of a +1/+1 counter or haste.)

Golgari Signet

Have

Progenitus

Protection from everything
If Progenitus would be put into a graveyard from anywhere, reveal Progenitus and shuffle it into its owner's library instead.

Snow-Covered Mountain

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Idyllic Tutor

Search your library for an enchantment card, reveal it, put it into your hand, then shuffle.

Vampiric Tutor

Search your library for a card, then shuffle and put that card on top. You lose 2 life.

Azorius Signet

Sapphire Medallion

Blue spells you cast cost {1} less to cast.

Command Tower

Gruul Signet

Selesnya Signet

Snow-Covered Swamp

Dimir Signet

Worldly Tutor

Search your library for a creature card, reveal it, then shuffle and put the card on top.

Jet Medallion

Black spells you cast cost {1} less to cast.

Profane Tutor

Suspend 2—{1}{B} (Rather than cast this card from your hand, pay {1}{B} and exile it with two time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.)
Search your library for a card, put that card into your hand, then shuffle.

Snow-Covered Island

Ruby Medallion

Red spells you cast cost {1} less to cast.

Izzet Signet

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice Commander's Sphere: Draw a card.

Snow-Covered Forest

Sol Ring

Enlightened Tutor

Search your library for an artifact or enchantment card, reveal it, then shuffle and put that card on top.

Snow-Covered Plains

Semblance Anvil

Imprint — When Semblance Anvil enters, you may exile a nonland card from your hand.
Spells you cast that share a card type with the exiled card cost {2} less to cast.

Simic Signet

Demonic Tutor

Search your library for a card, put that card into your hand, then shuffle.

Flaming Fist

Commander creatures you own have "Whenever this creature attacks, it gains double strike until end of turn."

Blade of Selves

Equipped creature has myriad. (Whenever it attacks, for each opponent other than defending player, you may create a token copy that's tapped and attacking that player or a planeswalker they control. Exile the tokens at end of combat.)
Equip {4}

Finest Hour

Exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.)
Whenever a creature you control attacks alone, if it's the first combat phase of the turn, untap that creature. After this phase, there is an additional combat phase.

Brave the Sands

Creatures you control have vigilance.
Each creature you control can block an additional creature each combat.