Case of the Locked Hothouse

You may play an additional land on each of your turns.
To solve — You control seven or more lands. (If unsolved, solve at the beginning of your end step.)
Solved — You may look at the top card of your library any time, and you may play lands and cast creature and enchantment spells from the top of your library.

Skyshroud Claim

Search your library for up to two Forest cards, put them onto the battlefield, then shuffle.

Forest

Snow-Covered Mountain

Aurora Phoenix

Flying
Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)
Whenever you cast a spell with cascade, return this card from your graveyard to your hand.

Steel Hellkite

Flying
{2}: This creature gets +1/+0 until end of turn.
{X}: Destroy each nonland permanent with mana value X whose controller was dealt combat damage by this creature this turn. Activate only once each turn.

Stalking Vengeance

Haste
Whenever another creature you control dies, it deals damage equal to its power to target player or planeswalker.

Rootbound Crag

This land enters tapped unless you control a Mountain or a Forest.
{T}: Add {R} or {G}.

Moraug, Fury of Akoum

Each creature you control gets +1/+0 for each time it has attacked this turn.
Landfall — Whenever a land you control enters, if it's your main phase, there's an additional combat phase after this phase. At the beginning of that combat, untap all creatures you control.

Spring-Leaf Avenger

Ninjutsu {3}{G} ({3}{G}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever this creature deals combat damage to a player, return target permanent card from your graveyard to your hand.

Hunting Wilds

Kicker {3}{G} (You may pay an additional {3}{G} as you cast this spell.)
Search your library for up to two Forest cards, put them onto the battlefield tapped, then shuffle.
If this spell was kicked, untap all Forests put onto the battlefield this way. They become 3/3 green creatures with haste that are still lands.

Sweet-Gum Recluse

Flash
Cascade
Reach
When this creature enters, put three +1/+1 counters on each of any number of target creatures that entered this turn.

Encroaching Dragonstorm

When this enchantment enters, search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.
When a Dragon you control enters, return this enchantment to its owner's hand.

Map the Frontier

Search your library for up to two basic land cards and/or Desert cards, put them onto the battlefield tapped, then shuffle.

Cosmium Confluence

Choose three. You may choose the same mode more than once.
• Search your library for a Cave card, put it onto the battlefield tapped, then shuffle.
• Put three +1/+1 counters on a Cave you control. It becomes a 0/0 Elemental creature with haste. It's still a land.
• Destroy target enchantment.

Etali, Primal Storm

Whenever Etali attacks, exile the top card of each player's library, then you may cast any number of spells from among those cards without paying their mana costs.

Emergent Woodwurm

Backup 3 (When this creature enters, put three +1/+1 counters on target creature. If that's another creature, it gains the following ability until end of turn.)
Whenever this creature attacks, look at the top X cards of your library, where X is its power. You may put a permanent card with mana value X or less from among them onto the battlefield. Put the rest on the bottom of your library in a random order.

Migration Path

Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.
Cycling {2} ({2}, Discard this card: Draw a card.)

Awakened Skyclave

Vigilance, haste
As long as this creature is on the battlefield, it's a land in addition to its other types.
{T}: Add one mana of any color.

Invasion of Zendikar

(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 this Siege enters, search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.

Invasion of Zendikar // Awakened Skyclave

Mirror March

Whenever a nontoken creature you control enters, flip a coin until you lose a flip. For each flip you won, create a token that's a copy of that creature. Those tokens gain haste. Exile them at the beginning of the next end step.

Screamer-Killer

Trample
Bio-Plasmic Scream — Whenever you cast a creature spell with mana value 5 or greater, this creature deals 5 damage to any target.

Command Tower

{T}: Add one mana of any color in your commander's color identity.

Kessig Wolf Run

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

Enduring Courage

Whenever another creature you control enters, it gets +2/+0 and gains haste until end of turn.
When Enduring Courage dies, if it was a creature, return it to the battlefield under its owner's control. It's an enchantment. (It's not a creature.)

Echoing Deeps

You may have this land enter tapped as a copy of any land card in a graveyard, except it's a Cave in addition to its other types.
{T}: Add {C}.

Beast Whisperer

Whenever you cast a creature spell, draw a card.

Bloodbraid Challenger

Cascade
Haste
Escape—{3}{R}{G}, Exile three other cards from your graveyard. (You may cast this card from your graveyard for its escape cost.)

Quartzwood Crasher

Trample
Whenever one or more creatures you control with trample deal combat damage to a player, create an X/X green Dinosaur Beast creature token with trample, where X is the amount of damage those creatures dealt to that player.

Annoyed Altisaur

Reach, trample
Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)

Ranger's Path

Search your library for up to two Forest cards, put them onto the battlefield tapped, then shuffle.

Terramorph

Search your library for a basic land card, put it onto the battlefield, then shuffle.
Rebound (If you cast this spell from your hand, exile it as it resolves. At the beginning of your next upkeep, you may cast this card from exile without paying its mana cost.)

Molten Primordial

Haste
When this creature enters, for each opponent, gain control of up to one target creature that player controls until end of turn. Untap those creatures. They gain haste until end of turn.

End-Raze Forerunners

Vigilance, trample, haste
When this creature enters, other creatures you control get +2/+2 and gain vigilance and trample until end of turn.

Garruk's Packleader

Whenever another creature you control with power 3 or greater enters, you may draw a card.

Panglacial Wurm

Trample
While you're searching your library, you may cast this card from your library.

Noise Marine

Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)
Sonic Blaster — When this creature enters, it deals damage equal to the number of spells you've cast this turn to any target.

Walk with the Ancestors

Return up to one target permanent card from your graveyard to your hand. Discover 4. (Exile cards from the top of your library until you exile a nonland card with mana value 4 or less. Cast it without paying its mana cost or put it into your hand. Put the rest on the bottom in a random order.)

Circuitous Route

Search your library for up to two basic land cards and/or Gate cards, put them onto the battlefield tapped, then shuffle.

Calamity, Galloping Inferno

Haste
Whenever Calamity attacks while saddled, choose a nonlegendary creature that saddled it this turn and create a tapped and attacking token that's a copy of it. Sacrifice that token at the beginning of the next end step. Repeat this process once.
Saddle 1

Cinder Glade

({T}: Add {R} or {G}.)
This land enters tapped unless you control two or more basic lands.

Volcanic Torrent

Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)
Volcanic Torrent deals X damage to each creature and planeswalker your opponents control, where X is the number of spells you've cast this turn.

Captivating Crew

{3}{R}: Gain control of target creature an opponent controls until end of turn. Untap that creature. It gains haste until end of turn. Activate only as a sorcery.

Bigger on the Inside

Enchant artifact or land
Enchanted permanent has "{T}: Target player adds two mana of any one color. The next spell they cast this turn has cascade." (When they cast their next spell, they exile cards from the top of their library until they exile a nonland card that costs less. They may cast it without paying its mana cost. They put the exiled cards on the bottom in a random order.)

Harmonize

Reach the Horizon

Search your library for up to two basic land cards and/or Town cards with different names, put them onto the battlefield tapped, then shuffle.

Natural Reclamation

Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)
Destroy target artifact or enchantment.

Rishkar's Expertise

Draw cards equal to the greatest power among creatures you control.
You may cast a spell with mana value 5 or less from your hand without paying its mana cost.

Radha, Heir to Keld

Whenever Radha attacks, you may add {R}{R}.
{T}: Add {G}.

Guardian Project

Whenever a nontoken creature you control enters, if it doesn't have the same name as another creature you control or a creature card in your graveyard, draw a card.

Trumpeting Carnosaur

Trample
When this creature enters, discover 5.
{2}{R}, Discard this card: It deals 3 damage to target creature or planeswalker.

Let the Galaxy Burn

Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)
Let the Galaxy Burn deals X plus 2 damage to each creature that didn't enter this turn.

Blighted Woodland

{T}: Add {C}.
{3}{G}, {T}, Sacrifice this land: Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.

Breaching Dragonstorm

When this enchantment enters, exile cards from the top of your library until you exile a nonland card. You may cast it without paying its mana cost if that spell's mana value is 8 or less. If you don't, put that card into your hand.
When a Dragon you control enters, return this enchantment to its owner's hand.

Mossfire Valley

Rockfall Vale

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

Cactusfolk Sureshot

Reach
Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)
At the beginning of combat on your turn, other creatures you control with power 4 or greater gain trample and haste until end of turn.

Thunderfoot Baloth

Trample
Lieutenant — As long as you control your commander, this creature gets +2/+2 and other creatures you control get +2/+2 and have trample.

Monstrous Vortex

Whenever you cast a creature spell with power 5 or greater, discover X, where X is that spell's mana value. (Exile cards from the top of your library until you exile a nonland card with that mana value or less. Cast it without paying its mana cost or put it into your hand. Put the rest on the bottom in a random order.)

Hidden Nursery

This land enters tapped.
{T}: Add {G}.
{4}{G}, {T}, Sacrifice this land: Discover 4. Activate only as a sorcery. (Exile cards from the top of your library until you exile a nonland card with mana value 4 or less. Cast it without paying its mana cost or put it into your hand. Put the rest on the bottom in a random order.)

Drakuseth, Maw of Flames

Flying
Whenever Drakuseth attacks, it deals 4 damage to any target and 3 damage to each of up to two other targets.

Rampaging Baloths

Trample
Landfall — Whenever a land you control enters, create a 4/4 green Beast creature token.

Pyrewood Gearhulk

Vigilance, menace
When this creature enters, other creatures you control get +2/+2 and gain vigilance and menace until end of turn. Damage can't be prevented this turn.

Verdant Sun's Avatar

Whenever this creature or another creature you control enters, you gain life equal to that creature's toughness.

Spearbreaker Behemoth

Indestructible
{1}: Target creature with power 5 or greater gains indestructible until end of turn.

Hidden Volcano

This land enters tapped.
{T}: Add {R}.
{4}{R}, {T}, Sacrifice this land: Discover 4. Activate only as a sorcery. (Exile cards from the top of your library until you exile a nonland card with mana value 4 or less. Cast it without paying its mana cost or put it into your hand. Put the rest on the bottom in a random order.)

Ogre Battledriver

Whenever another creature you control enters, that creature gets +2/+0 and gains haste until end of turn. (It can attack and {T} this turn.)

Karplusan Forest

{T}: Add {C}.
{T}: Add {R} or {G}. This land deals 1 damage to you.

Warstorm Surge

Whenever a creature you control enters, it deals damage equal to its power to any target.

Explosive Vegetation

Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.

Oliphaunt

Trample
Whenever this creature attacks, another target creature you control gets +2/+0 and gains trample until end of turn.
Mountaincycling {1} ({1}, Discard this card: Search your library for a Mountain card, reveal it, put it into your hand, then shuffle.)

Into the Time Vortex

Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)
Rebound (If you cast this spell from your hand, exile it as it resolves. At the beginning of your next upkeep, you may cast this card from exile without paying its mana cost.)

Scion of Calamity

Myriad (Whenever this creature attacks, for each opponent other than defending player, you may create a token copy that's tapped and attacking that player or a planeswalker they control. Exile the tokens at end of combat.)
Whenever this creature deals combat damage to a player, destroy target artifact or enchantment that player controls.

Game Trail

As this land enters, you may reveal a Mountain or Forest card from your hand. If you don't, this land enters tapped.
{T}: Add {R} or {G}.

Gruul Ragebeast

Whenever this creature or another creature you control enters, that creature fights target creature an opponent controls.

Snow-Covered Forest

Soul of the Harvest

Trample
Whenever another nontoken creature you control enters, you may draw a card.

Vastwood Surge

Kicker {4} (You may pay an additional {4} as you cast this spell.)
Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle. If this spell was kicked, put two +1/+1 counters on each creature you control.

Apex Devastator

Cascade, cascade, cascade, cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order. Multiple instances of cascade each trigger separately.)

Pit of Offerings

This land enters tapped.
When this land enters, exile up to three target cards from graveyards.
{T}: Add {C}.
{T}: Add one mana of any of the exiled cards' colors.