msem-instigator

Whenever you scry, tap target creature an opponent controls.
{2}{W}{U}: Scry 1. You gain 1 life.

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.)

Create three 1/1 colorless Servo artifact creature tokens.

Counter target nonenchantment spell.

Desperate Android enters tapped.
Whenever another artifact you control dies for the first time each turn, return Desperate Android from your graveyard to your hand.

Target creature you control deals damage equal to its power to target creature or planeswalker you don't control. Scry 1.

Flying, haste
{2}{B}: Devourer of Dread gets +1/+1 until end of turn. If there are three or more creature cards in your graveyard, put a +1/+1 counter on Devourer of Dread instead.

You may cast spells as though they had flash.
Whenever you cast a sorcery spell, each opponent loses 3 life unless they discard a card or sacrifice a nonland permanent.

You can't lose the game.
Whenever you draw a card, create a tapped Treasure token.
When you lose life, sacrifice that many permanents.

Flying
Ward—Pay 2 life. (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays 2 life.)
Whenever Dire Harpies of Odunos or another creature with flying you control enters, each opponent loses 1 life and you gain 1 life.

Chronicle (As this enters and after your draw step, add a lore counter. Stop after III.)
[Lore I-II] Until your next turn, up to one target creature can't attack or block and its activated abilities can't be activated.
[Lore III] Target opponent skips their next combat phase.

Doom deals 3 damage to any target and you gain 3 life.
Reconstruct {3}{B}{B} (You may cast this from your graveyard for its reconstruct cost reduced by the mana value of a permanent you sacrifice as you cast it this way. Then exile this.)
You may cast Doom from exile by paying {4}{B}{B}{B} rather than its mana cost. If you do, shuffle it into your library instead of putting it anywhere else as it resolves.

Deathtouch
When Doomed Explorer dies, create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)

At the beginning of your first main phase, add {R}.
Whenever a colossal ability puts one or more counters on a creature you control, Draconic Symphony deals 2 damage to any target.

When Drown in Apathy enters, exile target creature until Drown in Apathy leaves the battlefield. If a permanent would be returned to the battlefield this way, put it in its owner's hand instead.

All creatures get -2/-2 until end of turn. Scry 1.

Creatures you control enter with a +1/+1 counter on them if you spend three or more colors of mana to cast them.

Return up to six target cards in your graveyard that don't share colors to your hand.
Exile Earthly Ambitions.

Enchant creature
Enchanted creature has “Whenever this creature deals combat damage to a player, create a token that's a copy of it, except it's a 1/1 Reflection” and “When this creature leaves the battlefield, sacrifice all Reflections you control.”

Your opponents can't gain life.
Whenever you cast a noncreature spell, put a +1/+1 counter on Eidolon of the Arena.

Double strike
Whenever Eldan Jackson deals combat damage, return target permanent card with mana value 3 or less from your graveyard to the battlefield.

Colossal 2—{3}{R} (You may cast this for its colossal cost to have it enter with two +1/+1 counters; or pay {3}{R} as a sorcery: Put two +1/+1 counters on it if it has none.)
When Emberhound's colossal ability puts one or more counters on it, target creature can't block this turn.

Sacrifice a land: You may cast a spell from your hand without paying its mana cost. Activate this ability only once each turn.
Exile five land cards from your graveyard: Draw five cards. Exile the top ten cards of your library.

Whenever you cast a spell, if you cast it for an alternative cost or cast it from anywhere other than your hand, create two 1/1 blue Elemental creature tokens with flying. (Reconstruct and rhapsody are alternative costs, hybrid costs are not.)

Colossal 4—{4}{G}{G}{G} (You may cast this for its colossal cost to have it enter with four +1/+1 counters; or pay {4}{G}{G}{G} as a sorcery: Put four +1/+1 counters on it if it has none.)
Whenever a nontoken creature you control with a counter on it dies, create a 4/4 green Hydra creature token.