msem-instigator

{U}: Sea Strider gets +1/-1 until end of turn.
{U}: Sea Strider gets -1/+1 until end of turn.

{1}, {T}, Sacrifice Aureate Panorama: Search your library for a land card that could produce each color of mana, put it onto the battlefield, then shuffle.

Target player reveals their hand. Exile a nonland card from it and put a secret counter on it. As long as that card remains exiled, that player may pay {2} any time they could cast a sorcery to put it into their hand.
{X}{B}{B}, Exile Swipe Secrets from your graveyard: Until end of turn, you may cast target card you exiled with a secret counter on it and mana value X without paying its mana cost.

Exile target spell or nonland permanent. That card's owner casts it without paying its mana cost at the beginning of the next turn's upkeep.

Equipped creature has “Whenever this creature attacks, you may sacrifice Torch of Phoenixfire. When you do, Torch of Phoenixfire deals 3 damage to any target.”
Equip {1}

Tap X untapped Shamans you control: Ravik, Still-Smoke Seer deals X damage to any target and you gain X life.

Menace
Sacrifice another artifact: Scrap Buggy becomes an artifact creature until end of turn.
Crew 2 (Tap any number of creatures you control with total power 2 or greater: This Vehicle becomes an artifact creature until end of turn.)

At the beginning of each end step, if a creature left the battlefield this turn, you get a glory counter. (You lose glory counters before life. A player with ten or more glory counters wins the game.)
{2}{W}{U}: When target creature dies this turn, return that card to its owner's hand.

Menace
When this creature dies, create two tapped 3/2 colorless Eldrazi creature tokens. Put a stun counter on one of them.

Cycling {3} ({3}, Discard this card: Draw a card.)

Deathtouch
When Flesheater Vine enters, you may have it consume. If you do, put a +1/+1 counter on it and you gain 3 life. (To consume, sacrifice another creature or exile a creature card from your graveyard.)

Equipped creature gets +1/+1.
Whenever equipped creature becomes the target of a spell or ability an opponent controls, you may return Shawl of Warding to its owner's hand. If you do, counter that spell or ability.
Equip {2}

Put target creature into its owner's library second from the top.

Target creature gets -1/-1 until end of turn, a second target creature gets -2/-2 until end of turn, and a third target creature gets -3/-3 until end of turn.

Siphon (Each -1/-1 counter you put on your creatures up to their remaining toughness while casting this pays for {1}.)
Create a token that's a copy of target creature you control, except it enters with an additional -1/-1 counter on it.

Menace, haste

Target opponent shuffles a card from their hand into their library.

First strike, haste
Other creatures you control with flash or haste have first strike.

Enchant creature or planeswalker
You control enchanted permanent.
Permanents you control but don't own have hexproof.

Whenever Hero of Aer attacks, it gets +2/+1 until end of turn.

(As an Encounter enters, choose an opponent to protect it. You and others can attack it. When defense counters are removed, create a 0/0 Army token if you don't control one, then put that many +1/+1 counters on a Army you control.)
When Crisis in Danaj enters, return target creature an opponent controls to its owner's hand.

This spell costs {2} less to cast for each creature that died this turn.
Each player exiles all creature cards from their graveyard, then sacrifices each creature they control, then puts all creature cards they own exiled this way onto the battlefield. Exile Sea of Corpses.

Flying
Ward—{2}, Pay 2 life.
At the beginning of your end step, if a card was put into or left your graveyard this turn, put a +1/+1 counter on Tormentor of Graves.

Fang Den Bouncer can't be blocked by creatures with power 2 or less.

Enchant creature
Harness (You may tap a creature you control as you cast this spell. If you do, reduce this spell's mana cost by that creature's power.)
Enchanted creature doesn't untap during its controller's untap step.