If a creature spell you cast this turn was countered by a spell or ability an opponent controlled, you may pay rather than pay Summoning Trap's mana cost.
Look at the top seven cards of your library. You may put a creature card from among them onto the battlefield. Put the rest on the bottom of your library in any order.

Flying
: Add one mana of any color to your mana pool.

Emrakul, the Aeons Torn can't be countered.
When you cast Emrakul, take an extra turn after this one.
Flying, protection from colored spells, annihilator 6
When Emrakul is put into a graveyard from anywhere, its owner shuffles his or her graveyard into his or her library.

Knight of the Reliquary gets +1/+1 for each land card in your graveyard.
, Sacrifice a Forest or Plains: Search your library for a land card, put it onto the battlefield, then shuffle your library.

Landfall - Whenever a land enters the battlefield under your control, you may add one mana of any color to your mana pool.

When Nest Invader enters the battlefield, put a 0/1 colorless Eldrazi Spawn creature token onto the battlefield. It has "Sacrifice this creature: Add to your mana pool."

Exalted
: Add , , or to your mana pool.

Trample
Whenever Primeval Titan enters the battlefield or attacks, you may search your library for up to two land cards, put them onto the battlefield tapped, then shuffle your library.

, Pay 1 life, Sacrifice Misty Rainforest: Search your library for a Forest or Island card and put it onto the battlefield. Then shuffle your library.

Hideaway
: Add to your mana pool.
, : You may play the exiled card without paying its mana cost if you attacked with three or more creatures this turn.

Flying, first strike, lifelink, protection from Demons and from Dragons

, Pay 1 life, Sacrifice Verdant Catacombs: Search your library for a Swamp or Forest card and put it onto the battlefield. Then shuffle your library.

Stirring Wildwood enters the battlefield tapped.
: Add or to your mana pool.
: Until end of turn, Stirring Wildwood becomes a 3/4 green and white Elemental creature with reach. It's still a land.

Razorberge Thicket enters the battlefield tapped unless you control two or fewer other lands.
: Add or to your mana pool.

As Murmuring Bosk enters the battlefield, you may reveal a Treefolk card from your hand. If you don't, Murmuring Bosk enters the battlefield tapped.
: Add or to your mana pool. Murmuring Bosk deals 1 damage to you.

Sejiri Steppe enters the battlefield tapped.
When Sejiri Steppe enters the battlefield, target creature you control gains protection from the color of your choice until end of turn.
: Add to your mana pool.

: Add to your mana pool.
: Mutavault becomes a 2/2 creature with all creature types until end of turn. It's still a land.

Khalni Garden enters the battlefield tapped.
When Khalni Garden enters the battlefield, put a 0/1 green Plant creature token onto the battlefield.
: Add to your mana pool.

Hideaway
: Add to your mana pool.
, : You may play the exiled card without paying its mana cost if creatures you control have total power 10 or greater.

Protection from red
Sacrifice Burrenton Forge-Tender: Prevent all damage a red source of your choice would deal this turn.

Flash
Reach
When Cloudthresher enters the battlefield, it deals 2 damage to each creature with flying and each player.
Evoke

Noncreature spells with converted mana cost 4 or greater can't be cast.
Noncreature spells with in their mana costs can't be cast.

Flying
Activated abilities of creatures your opponents control can't be activated.

Exalted
, Sacrifice Qasali Pridemage: Destroy target artifact or enchantment.

Destroy target artifact or enchantment. Its controller gains 4 life.

Exile target creature. Its controller may search his or her library for a basic land card, put that card onto the battlefield tapped, then shuffle his or her library.

Destroy all creatures.