Fellwar Stone

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

Gamble

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

Covetous Dragon

Flying
When you control no artifacts, sacrifice Covetous Dragon.

Draco

Domain — This spell costs {2} less to cast for each basic land type among lands you control.
Flying
Domain — At the beginning of your upkeep, sacrifice Draco unless you pay {10}. This cost is reduced by {2} for each basic land type among lands you control.

Bloodfire Colossus

{R}, Sacrifice Bloodfire Colossus: It deals 6 damage to each creature and each player.

Thundermare

Haste (This creature can attack and {T} as soon as it comes under your control.)
When Thundermare enters the battlefield, tap all other creatures.

Darigaaz, the Igniter

Flying
Whenever Darigaaz, the Igniter deals combat damage to a player, you may pay {2}{R}. If you do, choose a color, then that player reveals their hand and Darigaaz deals damage to the player equal to the number of cards of that color revealed this way.

Crosis, the Purger

Flying
Whenever Crosis, the Purger deals combat damage to a player, you may pay {2}{B}. If you do, choose a color, then that player reveals their hand and discards all cards of that color.

Sneak Attack

{R}: You may put a creature card from your hand onto the battlefield. That creature gains haste. Sacrifice the creature at the beginning of the next end step.

Dragon Mage

Flying
Whenever Dragon Mage deals combat damage to a player, each player discards their hand, then draws seven cards.

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice Mind Stone: Draw a card.

Bladewing the Risen

Flying
When Bladewing the Risen enters the battlefield, you may return target Dragon permanent card from your graveyard to the battlefield.
{B}{R}: Dragon creatures get +1/+1 until end of turn.

Defense Grid

Each spell costs {3} more to cast except during its controller's turn.

Mountain

Butcher Orgg

You may assign Butcher Orgg's combat damage divided as you choose among defending player and/or any number of creatures they control.

Pyromancy

{3}, Discard a card at random: Pyromancy deals damage to any target equal to the mana value of the discarded card.

Pandemonium

Whenever a creature enters the battlefield, that creature's controller may have it deal damage equal to its power to any target of their choice.

Dragon Tyrant

Flying, trample
Double strike (This creature deals both first-strike and regular combat damage.)
At the beginning of your upkeep, sacrifice Dragon Tyrant unless you pay {R}{R}{R}{R}.
{R}: Dragon Tyrant gets +1/+0 until end of turn.

Ashen Firebeast

{1}{R}: Ashen Firebeast deals 1 damage to each creature without flying.

Shivan Hellkite

Flying (This creature can't be blocked except by creatures with flying or reach.)
{1}{R}: Shivan Hellkite deals 1 damage to any target.

Colossus of Sardia

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
Colossus of Sardia doesn't untap during your untap step.
{9}: Untap Colossus of Sardia. Activate only during your upkeep.

Crater Hellion

Echo {4}{R}{R} (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)
When Crater Hellion enters the battlefield, it deals 4 damage to each other creature.