Summoning Trap

If a creature spell you cast this turn was countered by a spell or ability an opponent controlled, you may pay {0} rather than pay this spell'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.

Wulfgar of Icewind Dale

Melee (Whenever this creature attacks, it gets +1/+1 until end of turn for each opponent you attacked this combat.)
If a creature you control attacking causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Druid Class

(Gain the next level as a sorcery to add its ability.)
Landfall — Whenever a land you control enters, you gain 1 life.
{2}{G}: Level 2
You may play an additional land on each of your turns.
{4}{G}: Level 3
When this Class becomes level 3, target land you control becomes a creature with haste and "This creature's power and toughness are each equal to the number of lands you control." It's still a land.

Kessig Wolf Run

{T}: Add {C}.
{X}{R}{G}, {T}: Target creature gets +X/+0 and gains trample until end of turn.

Copperline Gorge

Copperline Gorge enters tapped unless you control two or fewer other lands.
{T}: Add {R} or {G}.

Explore

You may play an additional land this turn.
Draw a card.

Primeval Titan

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

Rockfall Vale

Rockfall Vale enters tapped unless you control two or more other lands.
{T}: Add {R} or {G}.

Inferno Titan

{R}: Inferno Titan gets +1/+0 until end of turn.
Whenever Inferno Titan enters or attacks, it deals 3 damage divided as you choose among one, two, or three targets.

Raging Ravine

Raging Ravine enters tapped.
{T}: Add {R} or {G}.
{2}{R}{G}: Until end of turn, Raging Ravine becomes a 3/3 red and green Elemental creature with "Whenever this creature attacks, put a +1/+1 counter on it." It's still a land.

Fire-Lit Thicket

{T}: Add {C}.
{R/G}, {T}: Add {R}{R}, {R}{G}, or {G}{G}.

Inkmoth Nexus

{T}: Add {C}.
{1}: Inkmoth Nexus becomes a 1/1 Phyrexian Blinkmoth artifact creature with flying and infect until end of turn. It's still a land. (It deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Courser of Kruphix

Play with the top card of your library revealed.
You may play lands from the top of your library.
Landfall — Whenever a land you control enters, you gain 1 life.

Sweltering Suns

Sweltering Suns deals 3 damage to each creature.
Cycling {3} ({3}, Discard this card: Draw a card.)

Scale the Heights

Put a +1/+1 counter on up to one target creature. You gain 2 life. You may play an additional land this turn.
Draw a card.