Covetous Dragon

Flying
When you control no artifacts, sacrifice Covetous Dragon.

Ancient Tomb

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

Manifold Key

{1}, {T}: Untap another target artifact.
{3}, {T}: Target creature can't be blocked this turn.

Crumbling Sanctuary

If damage would be dealt to a player, that player exiles that many cards from the top of their library instead.

Shattering Pulse

Buyback {3} (You may pay an additional {3} as you cast this spell. If you do, put this card into your hand as it resolves.)
Destroy target artifact.

Strip Mine

{T}: Add {C}.
{T}, Sacrifice Strip Mine: Destroy target land.

Faithless Looting

Draw two cards, then discard two cards.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Earthquake

Earthquake deals X damage to each creature without flying and each player.

Spellshock

Whenever a player casts a spell, Spellshock deals 2 damage to that player.

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.

Wildfire

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

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.)

Avatar of Hope

If you have 3 or less life, this spell costs {6} less to cast.
Flying
Avatar of Hope can block any number of creatures.

Phyrexian Processor

As Phyrexian Processor enters, pay any amount of life.
{4}, {T}: Create an X/X black Phyrexian Minion creature token, where X is the life paid as Phyrexian Processor entered.

Fire Diamond

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

Rack and Ruin

Mountain

Grim Monolith

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

City of Brass

Whenever City of Brass becomes tapped, it deals 1 damage to you.
{T}: Add one mana of any color.