msem-instigator

Flash (You may cast this spell any time you could cast an instant.)
When Dazzling Voidmage enters, you may return target attacking creature to its owner's hand.

Counter target spell if it wasn't cast from a player's hand.

Engorge (As this enters, mill three cards, then exile a card from among the milled cards.)
When Deadland Summoner dies, you may put the card it engorged into your hand. If that card is an instant or sorcery card, you may instead cast it without paying its mana cost.

Flying
When Dealer of Pointed Fortunes enters, proliferate. (Choose any number of permanents and/or players with counters on them, then give each another counter of each kind already there.)

Enchant creature
When Deathless Conscription enters, untap enchanted creature.
You control enchanted creature.

When Debt Dignitary enters, tap target nonland permanent. That permanent doesn't untap during its controller's untap step for as long as you control Debt Dignitary.

Flash
When Decisive Arcanist enters, you may cast target modal instant or sorcery card in your graveyard. Exile that card instead of putting it into your graveyard as it resolves.

Counter target creature spell, planeswalker spell, or activated ability.

Draw a card. Investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

Counter target spell with mana value 3 or less. If a spell is countered this way, return it to its owner's hand instead of putting it anywhere else.

Enchant creature
Enchanted creature doesn't untap during its controller's untap step.
At the beginning of the upkeep of enchanted creature's controller, that player mills a card.

Exile target creature. Return that card to its owner's hand at the beginning of its owner's next end step.

Deep-Sea Terror can't attack unless seven or more cards are in your graveyard.

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

Defender
Sacrifice two Islands: Deepsea Denizen loses defender until end of turn.

Deft Goldsnatch can't be blocked.

Enchant non-Camel creature
When Dehydrate enters, draw a card.
Enchanted creature gets -1/-0.

This spell costs {1} less to cast for each time you catalyzed this turn.
Counter target spell unless its controller pays {X}.

Whenever Deluge Crab perseveres, target opponent mills three cards. (A creature perseveres when it survives damage.)

Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)
Each creature you control with a counter on it has ward {2}. (If a creature has multiple instances of ward, each triggers separately.)

When Delugic Surger enters, if you control another Elemental, return target instant or sorcery card from your graveyard to your hand.

(As this Saga enters and after your draw step, ad a lore counter. Sacrifice after III.)
I, II — Create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)
III — You may sacrifice any number of artifacts. If you do, draw that many cards.

When Demented Brainiac enters and at the beginning of your upkeep, each opponent mills two cards.
{U}, Sacrifice Demented Brainiac: Exile each opponent's graveyard. Until end of turn, you may cast instant and sorcery spells exiled this way, and you may spend mana as though it were mana of any color to cast them.

When Demonqueller Mage enters, gain control of target creature with power 2 or less until Demonqueller Mage leaves the battlefield.

Tap up to two target creatures.
Cycling {1}{U} ({1}{U}, Discard this card: Draw a card.)
When you cycle Denied Attempt, you may tap target creature.