msem-instigator

Deadwood Grove enters tapped.
{T}: Add {B} or {G}.
{1}{B}{G}: Until end of turn, Deadwood Grove becomes a 2/3 black and green Horror creature with with deathtouch and “Whenever this creature attacks or blocks, torment yourself.” It's still a land. (To torment yourself, lose 3 life unless you discard a card or sacrifice a nonland permanent.)

{T}: Add {C}.
{T}, Exile two cards from your graveyard: Add {W} or {B}.

{T}: Put a flood counter on Decanter of Endless Rivers. Add {U} for each flood counter on it.

Decayed Bedchamber enters tapped.
When Decayed Bedchamber enters, look at the top card of your library. You may put it into your graveyard.
{T}: Add {B} or {G}.

{T}, Sacrifice Decrepit Crags: Search your library for a Swamp or Mountain card and put it onto the battlefield tapped, then shuffle.

When Dedicated Waypoint enters, create a 1/1 white Scout creature token.
{T}: Add {R}, {W}, or {B}.

Deepdrinker's Domain enters tapped.
{T}: Add {U}.

At the beginning of your upkeep, choose an opponent. That player creates a 3/2 colorless Horror creature token.
{2}: Target opponent gains control of Deepdrinker's Effigy.

Deeplife Cavern enters tapped unless you control a Forest.
{T}: Add {U} or {B}.

{T}: Add {C}.
{3}{R}: Until end of turn, Defect's Precinct becomes a 3/3 creature. It's still a land. It has trample if {G} was spent to activate this ability, has vigilance if {W} was spent, and has hexproof if {U} was spent.

Whenever you cast a spell, if it shared a color with the last spell you cast this turn, put two +1/+1 counters on Defected Android.

Flying

At the beginning of each player's end step, that player sacrifices a permanent.

As Den of Vice enters, you may pay 3 life. If you don't, it enters tapped.
{T}: Add {U}, {B}, or {R}.

{4}{B}: Depthlight Beacon gets +1/+1 and gains lifelink until end of turn.
Cycling {2/B} ({2/B}, Discard this card: Draw a card.)

({T}: Add {R}.)
Derelict Amphitheatre enters tapped.
{R}, {T}, Reveal a red card from your hand: Scry 1.

{T}: Add one mana of any color.
When you tap Derelict Town for mana, return it to its owner's hand.

Defender
Whenever Derelict Watcher or another Scarecrow you control enters, create a 1/1 black Bird creature token with flying.

Descended Countryside enters tapped.
{T}: Add {G} or {W}.
Morph {2} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Descended Delta enters tapped.
{T}: Add {U} or {R}.
Morph {2} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Descended Fissure enters tapped.
{T}: Add {B} or {R}.
Morph {2} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Descended Glacier enters tapped.
{T}: Add {W} or {U}.
Morph {2} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Descended Gorge enters tapped.
{T}: Add {R} or {G}.
Morph {2} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Descended Hollow enters tapped.
{T}: Add {U} or {B}.
Morph {2} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Descended Marsh enters tapped.
{T}: Add {B} or {G}.
Morph {2} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)