Counterspell

Curiosity

Enchant creature
Whenever enchanted creature deals damage to an opponent, you may draw a card.

Mountain

Training Center

Training Center enters tapped unless you have two or more opponents.
{T}: Add {U} or {R}.

Sol Ring

Shao Jun

Leap Strike — During your turn, Shao Jun has flying and first strike.
Rope Dart — Tap two untapped artifacts you control: Shao Jun deals 1 damage to each opponent.

Thought Vessel

You have no maximum hand size.
{T}: Add {C}.

Fellwar Stone

{T}: Add one mana of any color that a land an opponent controls could produce.

Sulfur Falls

Sulfur Falls enters tapped unless you control an Island or a Mountain.
{T}: Add {U} or {R}.

Izzet Signet

Reliquary Tower

An Offer You Can't Refuse

Counter target noncreature spell. Its controller creates two Treasure tokens. (They're artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")

Dramatic Reversal

Untap all nonland permanents you control.

Arcane Signet

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

Command Tower

Blasphemous Act

This spell costs {1} less to cast for each creature on the battlefield.
Blasphemous Act deals 13 damage to each creature.

Loyal Inventor

Vigilance
When Loyal Inventor enters, you may search your library for an artifact card, reveal it, then shuffle. Put that card into your hand if you control an Assassin. Otherwise, put that card on top of your library.