Realm-Scorcher Hellkite

Bargain (You may sacrifice an artifact, enchantment, or token as you cast this spell.)
Flying, haste
When this creature enters, if it was bargained, add four mana in any combination of colors.
{1}{R}: This creature deals 1 damage to any target.

Agatha's Soul Cauldron

You may spend mana as though it were mana of any color to activate abilities of creatures you control.
Creatures you control with +1/+1 counters on them have all activated abilities of all creature cards exiled with Agatha's Soul Cauldron.
{T}: Exile target card from a graveyard. When a creature card is exiled this way, put a +1/+1 counter on target creature you control.

Zealot of the God-Pharaoh

{4}{R}: This creature deals 2 damage to target opponent or planeswalker.

Mountain

Training Grounds

Activated abilities of creatures you control cost {2} less to activate. This effect can't reduce the mana in that cost to less than one mana.

Goblin Engineer

When this creature enters, you may search your library for an artifact card, put it into your graveyard, then shuffle.
{R}, {T}, Sacrifice an artifact: Return target artifact card with mana value 3 or less from your graveyard to the battlefield.

Harnfel, Horn of Bounty

Discard a card: Exile the top two cards of your library. You may play those cards this turn.

Birgi, God of Storytelling

Whenever you cast a spell, add {R}. Until end of turn, you don't lose this mana as steps and phases end.
Creatures you control can boast twice during each of your turns rather than once.

Birgi, God of Storytelling // Harnfel, Horn of Bounty

Dualcaster Mage

Flash
When this creature enters, copy target instant or sorcery spell. You may choose new targets for the copy.

Olivia's Attendants

Menace
Whenever this creature deals damage, create that many Blood tokens. (They're artifacts with "{1}, {T}, Discard a card, Sacrifice this token: Draw a card.")
{2}{R}: This creature deals 1 damage to any target.

Snap

Return target creature to its owner's hand. Untap up to two lands.

Triskelion

This creature enters with three +1/+1 counters on it.
Remove a +1/+1 counter from this creature: It deals 1 damage to any target.

Walking Ballista

This creature enters with X +1/+1 counters on it.
{4}: Put a +1/+1 counter on this creature.
Remove a +1/+1 counter from this creature: It deals 1 damage to any target.

Helm of Awakening

Dalakos, Crafter of Wonders

{T}: Add {C}{C}. Spend this mana only to cast artifact spells or activate abilities of artifacts.
Equipped creatures you control have flying and haste.

Skarrgan Hellkite

Riot (This creature enters with your choice of a +1/+1 counter or haste.)
Flying
{3}{R}: This creature deals 2 damage divided as you choose among one or two targets. Activate only if this creature has a +1/+1 counter on it.

Hoarding Dragon

Flying
When this creature enters, you may search your library for an artifact card, exile it, then shuffle.
When this creature dies, you may put the exiled card into its owner's hand.

Izzet Guildgate

This land enters tapped.
{T}: Add {U} or {R}.

Heartstone

Activated abilities of creatures cost {1} less to activate. This effect can't reduce the mana in that cost to less than one mana.

Grinning Ignus

{R}, Return this creature to its owner's hand: Add {C}{C}{R}. Activate only as a sorcery.

Knacksaw Clique

Flying
{1}{U}, {Q}: Target opponent exiles the top card of their library. Until end of turn, you may play that card. ({Q} is the untap symbol.)

Omen Hawker

{T}: Add {C}{U}. Spend this mana only to activate abilities.

War Elemental

When this creature enters, sacrifice it unless an opponent was dealt damage this turn.
Whenever an opponent is dealt damage, put that many +1/+1 counters on this creature.