Magmatic Chasm

Creatures without flying can't block this turn.

Ornithopter

Castle Embereth

Castle Embereth enters tapped unless you control a Mountain.
{T}: Add {R}.
{1}{R}{R}, {T}: Creatures you control get +1/+0 until end of turn.

Mountain

Voldaren Epicure

When Voldaren Epicure enters, it deals 1 damage to each opponent. Create a Blood token. (It's an artifact with "{1}, {T}, Discard a card, Sacrifice this artifact: Draw a card.")

Burning-Tree Emissary

When Burning-Tree Emissary enters, add {R}{G}.

Lightshield Array

At the beginning of your end step, put a +1/+1 counter on each creature that attacked this turn.
Sacrifice Lightshield Array: Creatures you control gain hexproof and indestructible until end of turn.

Invasion of Gobakhan

(As a Siege enters, choose an opponent to protect it. You and others can attack it. When it's defeated, exile it, then cast it transformed.)
When Invasion of Gobakhan enters, look at target opponent's hand. You may exile a nonland card from it. For as long as that card remains exiled, its owner may play it. A spell cast this way costs {2} more to cast.

Invasion of Gobakhan // Lightshield Array

Knight-Errant of Eos

Convoke
When Knight-Errant of Eos enters, look at the top six cards of your library. You may reveal up to two creature cards with mana value X or less from among them, where X is the number of creatures that convoked Knight-Errant of Eos. Put the revealed cards into your hand, then shuffle.

Gleeful Demolition

Destroy target artifact. If you controlled that artifact, create three 1/1 red Phyrexian Goblin creature tokens.

Chop Down

Destroy target creature with power 4 or greater. (Then exile this card. You may cast the creature later from exile.)

Giant Killer

Giant Killer // Chop Down

Battlefield Forge

{T}: Add {C}.
{T}: Add {R} or {W}. Battlefield Forge deals 1 damage to you.

Wedding Festivity

Wedding Announcement

At the beginning of your end step, put an invitation counter on Wedding Announcement. If you attacked with two or more creatures this turn, draw a card. Otherwise, create a 1/1 white Human creature token. Then if Wedding Announcement has three or more invitation counters on it, transform it.

Wedding Announcement // Wedding Festivity

Forge Devil

When Forge Devil enters, it deals 1 damage to target creature and 1 damage to you.

Resolute Reinforcements

Flash (You may cast this spell any time you could cast an instant.)
When this creature enters, create a 1/1 white Soldier creature token.

Mana Confluence

{T}, Pay 1 life: Add one mana of any color.

Thalia, Guardian of Thraben

First strike
Noncreature spells cost {1} more to cast.

Reckless Bushwhacker

Surge {1}{R} (You may cast this spell for its surge cost if you or a teammate has cast another spell this turn.)
Haste
When Reckless Bushwhacker enters, if its surge cost was paid, other creatures you control get +1/+0 and gain haste until end of turn.

Den of the Bugbear

If you control two or more other lands, Den of the Bugbear enters tapped.
{T}: Add {R}.
{3}{R}: Until end of turn, Den of the Bugbear becomes a 3/2 red Goblin creature with "Whenever this creature attacks, create a 1/1 red Goblin creature token that's tapped and attacking." It's still a land.

Venerated Loxodon

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
When Venerated Loxodon enters, put a +1/+1 counter on each creature that convoked it.

Sacred Foundry

({T}: Add {R} or {W}.)
As Sacred Foundry enters, you may pay 2 life. If you don't, it enters tapped.

Cathar Commando

Flash (You may cast this spell any time you could cast an instant.)
{1}, Sacrifice this creature: Destroy target artifact or enchantment.

Sokenzan, Crucible of Defiance

{T}: Add {R}.
Channel — {3}{R}, Discard Sokenzan, Crucible of Defiance: Create two 1/1 colorless Spirit creature tokens. They gain haste until end of turn. This ability costs {1} less to activate for each legendary creature you control.

Inspiring Vantage

Inspiring Vantage enters tapped unless you control two or fewer other lands.
{T}: Add {R} or {W}.

Thraben Inspector

When Thraben Inspector enters, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")