Deadly Cover-Up

As an additional cost to cast this spell, you may collect evidence 6.
Destroy all creatures. If evidence was collected, exile a card from an opponent's graveyard. Then search its owner's graveyard, hand, and library for any number of cards with that name and exile them. That player shuffles, then draws a card for each card exiled from their hand this way.

Dance of the Tumbleweeds

Spree (Choose one or more additional costs.)
+ {1} — Search your library for a basic land card or a Desert card, put it onto the battlefield, then shuffle.
+ {3} — Create an X/X green Elemental creature token, where X is the number of lands you control.

Spinewoods Armadillo

Reach
Ward {3} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {3}.)
{1}{G}, Discard Spinewoods Armadillo: Search your library for a basic land card or a Desert card, reveal it, put it into your hand, then shuffle. You gain 3 life.

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.

Mirage Mesa

Mirage Mesa enters tapped. As it enters, choose a color.
{T}: Add one mana of the chosen color.

Desert's Due

Target creature gets -2/-2 until end of turn. It gets an additional -1/-1 until end of turn for each Desert you control.

Arid Archway

Arid Archway enters tapped.
When Arid Archway enters, return a land you control to its owner's hand. If another Desert was returned this way, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
{T}: Add {C}{C}.

Sandstorm Verge

{T}: Add {C}.
{3}, {T}: Target creature can't block this turn. Activate only as a sorcery.

Doppelgang

For each of X target permanents, create X tokens that are copies of that permanent.

Festering Gulch

Festering Gulch enters tapped.
When Festering Gulch enters, it deals 1 damage to target opponent.
{T}: Add {B} or {G}.

Conduit Pylons

When Conduit Pylons enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
{T}: Add {C}.
{1}, {T}: Add one mana of any color.

Three Steps Ahead

Spree (Choose one or more additional costs.)
+ {1}{U} — Counter target spell.
+ {3} — Create a token that's a copy of target artifact or creature you control.
+ {2} — Draw two cards, then discard a card.

Colossal Rattlewurm

Colossal Rattlewurm has flash as long as you control a Desert.
Trample
{1}{G}, Exile Colossal Rattlewurm from your graveyard: Search your library for a Desert card, put it onto the battlefield tapped, then shuffle.

Spelunking

When Spelunking enters, draw a card, then you may put a land card from your hand onto the battlefield. If you put a Cave onto the battlefield this way, you gain 4 life.
Lands you control enter untapped.

Lush Oasis

Lush Oasis enters tapped.
When Lush Oasis enters, it deals 1 damage to target opponent.
{T}: Add {G} or {U}.

Outcaster Greenblade

When Outcaster Greenblade enters, search your library for a basic land card or a Desert card, reveal it, put it into your hand, then shuffle.
Outcaster Greenblade gets +1/+1 for each Desert you control.

Soured Springs

Soured Springs enters tapped.
When Soured Springs enters, it deals 1 damage to target opponent.
{T}: Add {U} or {B}.

Chimil, the Inner Sun

Spells you control can't be countered.
At the beginning of your end step, discover 5. (Exile cards from the top of your library until you exile a nonland card with mana value 5 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.)