Sandsteppe Citadel

This land enters tapped.
{T}: Add {W}, {B}, or {G}.

Seaside Citadel

This land enters tapped.
{T}: Add {G}, {W}, or {U}.

Opulent Palace

This land enters tapped.
{T}: Add {B}, {G}, or {U}.

Return the Favor

Spree (Choose one or more additional costs.)
+ {1} — Copy target instant spell, sorcery spell, activated ability, or triggered ability. You may choose new targets for the copy.
+ {1} — Change the target of target spell or ability with a single target.

Aetherflux Reservoir

Whenever you cast a spell, you gain 1 life for each spell you've cast this turn.
Pay 50 life: This artifact deals 50 damage to any target.

Nomad Outpost

This land enters tapped.
{T}: Add {R}, {W}, or {B}.

Arcane Sanctum

This land enters tapped.
{T}: Add {W}, {U}, or {B}.

Crumbling Necropolis

This land enters tapped.
{T}: Add {U}, {B}, or {R}.

Ruby Medallion

Red spells you cast cost {1} less to cast.

Jungle Shrine

This land enters tapped.
{T}: Add {R}, {G}, or {W}.

Yavimaya, Cradle of Growth

Each land is a Forest in addition to its other land types.

Savage Lands

This land enters tapped.
{T}: Add {B}, {R}, or {G}.

Mystic Monastery

This land enters tapped.
{T}: Add {U}, {R}, or {W}.

Strike It Rich

Create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)