Mishra's Helix

Cursed Scroll

{3}, {T}: Choose a card name, then reveal a card at random from your hand. If that card has the chosen name, Cursed Scroll deals 2 damage to any target.

Voltaic Key

Temporal Aperture

{5}, {T}: Shuffle your library, then reveal the top card. Until end of turn, for as long as that card remains on top of your library, play with the top card of your library revealed and you may play that card without paying its mana cost. (If it has X in its mana cost, X is 0.)

Karn, Silver Golem

Whenever Karn, Silver Golem blocks or becomes blocked, it gets -4/+4 until end of turn.
{1}: Target noncreature artifact becomes an artifact creature with power and toughness each equal to its mana value until end of turn.

City of Traitors

When you play another land, sacrifice City of Traitors.
{T}: Add {C}{C}.

Mountain

Covetous Dragon

Flying
When you control no artifacts, sacrifice Covetous Dragon.

Thran Dynamo

Wildfire

Each player sacrifices four lands of their choice. Wildfire deals 4 damage to each creature.

Ancient Tomb

{T}: Add {C}{C}. Ancient Tomb deals 2 damage to you.

Fire Diamond

Fire Diamond enters tapped.
{T}: Add {R}.

Worn Powerstone

Worn Powerstone enters tapped.
{T}: Add {C}{C}.

Grim Monolith

Grim Monolith doesn't untap during your untap step.
{T}: Add {C}{C}{C}.
{4}: Untap Grim Monolith.

Masticore

At the beginning of your upkeep, sacrifice Masticore unless you discard a card.
{2}: Masticore deals 1 damage to target creature.
{2}: Regenerate Masticore.