msem-instigator

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.

Flying, haste
Whenever The Branded Usurper attacks, it deals 2 damage to any target.
If you would lose the game, instead exile The Branded Usurper. Your life total becomes 0. Until an opponent's next turn, you can't lose the game and you can't gain life. Take an extra turn after this one.

(Transform this if it's not attached to a creature. Pay {3}{G} as a sorcery to unattach it.)
Enchant creature you control
Elven Mount's rider gets +3/+3 and has trample.

Flying
Whenever another creature enters, you gain 1 life.

If you would lose unspent mana, that mana becomes colorless instead.

Creatures you control have deathtouch as long as they're attacking.
[+1]: Target creature you control must be blocked this turn if able.
[–2]: Create two 1/1 white Human creature tokens.
[–X]: Destroy target artifact or enchantment with mana value X and all other permanents with the same name as that permanent.

I, II — Target creature you control gets +2/+0 and gains menace until end of turn.
Discovery — Attacking creatures you control get +2/+0 and have menace.

When you cast this spell, each other player may copy it.
Exile the top seven cards of an opponent's library. Until the end of your next turn, you may play those cards, and you may spend mana as though it was mana of any type to cast those spells.

Gestalt (When this or another creature enters under your control, you may merge it with the one in play, keeping counters and attachments. They become the permanent on top plus all abilities from under it.)
This creature gets +2/+2 as long as it's merged with another card or token.

As Scrolls of Succession enters, choose a creature type.
Creatures you control of the chosen type get +1/+1.
{2}, {T}: Draw a card. Then discard a card unless you control three or more creatures of the chosen type.

{T}, Sacrifice a creature: Conjure a card named Data-Point into your hand. Activate only as a sorcery. (It's a sorcery that costs {2} with “Draw a card.”)

Golden age (If you cast an instant or sorcery spell, activated a nonmana ability, and attacked this turn, enter a renaissance for this game.)
Search your library for up to three creature cards with different mana values 4 or less, reveal them, put them into your hand, then shuffle. If you're in a renaissance, you may put one of those cards onto the battlefield instead of into your hand.

When Unburdening Priest enters, you may exile any number of creatures you control not named Unburdening Priest, then return those cards to the battlefield under your control.

Target creature you control gains hexproof until end of turn. Scry 1.

As an additional cost to cast this spell, return a creature you control to its owner's hand.
Counter target spell.

Whenever another creature you control dies, each other player sacrifices a creature.

Puzzlebox (Begin the game with this and another card you own from outside the game in the command zone, locked. That card is face down until you unlock this.)
When the fourth spell of a turn is cast, you may unlock Mirror Cipher. If the revealed card is an instant or sorcery card, cast it without paying its mana cost and copy it. You may choose new targets for the copy.

Menace
Whenever CySec Blacksuit deals combat damage to a player or planeswalker, create a Function token with “Choose a nonland card exiled by this spell. For as long as that card is exiled, you may cast it and you mana of any type can be spent to cast that spell.” (It's an enchantment. As you cast an instant or sorcery spell, sacrifice any number of Functions to add their effects to that spell.)

This spell costs {1} less to cast for each creature card in your graveyard.
Trample

Untap all creatures you control.
Draw a card.

Menace, haste
Whenever Manic River-Fishers attacks, you may search defending player's library for an instant or sorcery card that shares a name with a card in their graveyard and cast it without paying its mana cost. That player shuffles.

You may play Tectonic Chateau from your graveyard as long as seven or more cards are in your graveyard.
Tectonic Chateau enters tapped.
{T}: Add {R} or {W}.
Cycling {1}{R}{W} ({1}{R}{W}, Discard this card: Draw a card.)

({T}: Add {W}.)
Bygone Guardian enters tapped.
Vigilance
{2}{W}{W}: Bygone Guardian becomes a creature in addition to its other types until end of turn.

{T}: Add {C}.
{T}, Sacrifice a creature: Add one mana of any color.

Primal {U} (During your turn, you may cast this spell for {U} instead of playing a land.)
Counter target spell.