msem-instigator

Whenever you cast an instant or sorcery spell, you may untap Duela Science Kit.
{T}, Tap an untapped creature you control: Catalyze. (The next spell you cast this turn costs {1} less to cast.)

Equipped creature gets +1/+0 and has first strike.
As long as another artifact named Dueling Blades is attached to a creature you control, equipped creature has double strike.
Equip {1}

First strike, menace
Whenever Dueling Duo or another creature you control becomes blocked, that creature deals 1 damage to each creature blocking it.

Untapped creatures you control get +1/+1.
Soldiers you control have vigilance.

Vigilance
Whenever an opponent casts a spell, create a Treasure token unless that player pays {1}, then create a 1/1 white Merfolk creature token unless that player pays {1}.
{W}{U}{B}{R}{G}, {T}: Other creatures you control get +3/+3 and gain vigilance and indestructible until end of turn.

As Duke Gerard Hoff enters, an opponent gains control of it.
Duke Gerard Hoff can't attack its owner or planeswalkers that player controls.
Creatures your opponents control get +2/+1.

Deathtouch
At the beginning of each opponent's upkeep, that player loses 1 life.

{3}{R}: Target creature can't be blocked this turn if it's an artifact creature or has power 2 or less.

{T}, Sacrifice an artifact or creature: Each opponent loses 1 life and you gain 1 life.

Dulled Ghost can't be blocked by creatures which have power less than their toughness.
At the beginning of your end step, exile up to one target nonland permanent you control, then return it to the battlefield under its owner's control. If that permanent was tapped, each opponent discards a card.

Lifelink
Vanishing 1 (This creature enters with a time counter on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
Whenever another creature you control dies, put a time counter on Dulling Necromancer.

When Duncaster Nightwatcher enters and whenever you cast a noncreature spell, create a 1/1 colorless Human creature token.
Whenever you attack with three or more creatures, return target noncreature, nonland card with mana value 3 or less from your graveyard to your hand.

Enchant creature
Enchanted creature gets +2/+2 and can't be blocked as long as defending player controls a Desert.

Reach (This creature can block creatures with flying.)

Assault {1}{G} (Whenever this attacks, if it has no +1/+1 counters on it, you may pay its assault cost to put a +1/+1 counter on it.)
When Dune Tromper assaults, it gains trample until end of turn.

Flying
When Dune Wraith enters, distribute two +1/+1 counters among Spirits you control.

When Dunecrest Pariah enters, you may search your library for a basic land or Desert card, reveal it, put it into your hand, then shuffle.
{T}, Sacrifice Dunecrest Pariah: You may put a land card from your hand onto the battlefield tapped.

At the beginning of your upkeep, choose one —
• Create a colorless artifact token named Etherium Cell with “{T}, Sacrifice this artifact: Add one mana of any color.”
• Put a +1/+1 counter on another target artifact. It becomes a 0/0 Construct artifact creature if it isn't a creature.

Lifelink
Erratic (When this creature dies, reveal the top four cards of your library. Put a creature card that costs less than this revealed this way onto the battlefield and the rest on the bottom in a random order.)
Mirage {2}{W}{W} (You may cast this spell as though it had flash for its mirage cost. If you do, sacrifice it at the beginning of the next cleanup step.)

Menace
Whenever a creature you control deals combat damage to a player, exile the top card of that player's library. They lose life equal to that card's mana value.

Whenever you scry, put a +1/+1 counter on Dunesea Cartographer for each card you looked at while scrying this way.
{3}{W}{U}: Scry 2.

Dunesea Expanse enters tapped unless you control another Desert.
{T}: Add {W} or {U}.

Vigilance, ward {2}
{1}{G}, {T}: Put a +1/+1 counter on Dunetreader Tortoise. Activate only as a sorcery.

Copy target spell. You may choose new targets for the copy. (A copy of a permanent spell becomes a token.)

Flash
When Duplicated Dismantler enters, if you cast another spell this turn, return target spell to its owner's hand.