msem-instigator

If a card would be put into an opponent's graveyard from anywhere, instead that card is revealed and put on the bottom of that player's library.
Unveil {3}{G}{W} ({3}{G}{W}: Transform this. Unveil only as a sorcery.)

Whenever Starfall Instructor attacks, harmonize. (Trigger up to one harmony of a permanent you control.)
Harmony — Each opponent loses 2 life.

Reveal the top five cards of your library. An opponent separates those cards into two piles. Put one pile into your hand. You may cast a nonland card with mana value 3 or less from the other pile without paying its mana cost, then put that pile into your graveyard.

When you unveil Starlight Guardian, you may put target card from your graveyard on top of your library.
If a card would be put into an opponent's graveyard from anywhere, exile that card instead.

Flying
Creatures you control have vigilance.
At the beginning of combat on your turn, you may tap target creature.
Morph {4}{W}

Each player chooses up to half the creatures they control, then sacrifices the rest.

Menace
Discard a creature card or sacrifice a creature or exile a creature card from your graveyard: Put a +1/+1 counter on Starving Stalker. Activate only once each turn.

You may exile cards you own as you reveal them. (You see the card before you exile it.)
During each of your turns, you may cast a card exiled with Starwing Nebula.

Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

Prowess
Whenever Steamwalker attacks, you may discard a card. If you do, draw a card, then catalyze. (The next spell you cast this turn costs {1} less to cast.)

Flying
Other creatures you control with flying get +2/+2.

Exile two target creatures, planeswalkers and/or enchantments, then return one of those cards to the battlefield under its owner's control.

Target opponent discards a card at random. If that card's mana value is 3 or less, you may cast it without paying its mana cost.

When Still-Smoke Sojourners enters, remove all counters from target player or permanent. That player or that permanent's controller loses life equal to the number of counters removed this way.

Stinging Swordfish has first strike as long as it's attacking.
When Stinging Swordfish dies, create an Equipment enchantment artifact token named Fish Sword with “Equipped creature gets +3/+1,” “Equipped creature has first strike as long as it's attacking,” and equip {2}. You may attach that token to a creature you control.

Flying
Whenever you cast your first spell each turn, add {U}{U}, {U}{R}, or {R}{R}.
Whenever you cast your second spell each turn, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)
Whenever you cast your third spell each turn, Stirring Igmel deals 3 damage to each opponent.

Create a 2/2 red and white Cat Knight creature token. Creatures you control get +1/+1 and gain haste until end of turn.

Whenever you cast a creature spell, you may return target nontoken creature you control with a different name to its owner's hand. If you do, copy that spell. (A copy of a creature spell becomes a token.)

When Stolen Innovations enters, target opponent reveals their hand. You choose an instant or sorcery card from that player's hand or graveyard and exile it.
You may cast each spell you cast from your hand as a copy of the exiled card. You may spend mana as though it were mana of any color to cast spells this way.

Look at target opponent's hand. You may cast a card from that player's hand or graveyard, and you may spend mana as though it were of any type to cast that card. If you cast a card from that player's hand this way, that player draws a card.

Reach
Stonebark Incinerator gets +2/+0 and has trample as long as you control a Dwarf.
Stonebark Incinerator gets +0/+2 and has vigilance as long as you control a Elf.

Flying, haste
Whenever you cast an instant or sorcery spell, create a token that's a copy of Stormcall Thunderbird.

Flying, haste
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

At the beginning of your upkeep, you may pay 2 life. If you do, exile the top card of target opponent's library. If a nonland card is exiled this way, copy it. You may cast the copy. (You still pay its costs, including color. Copies of permanents enter as tokens.)

Target creature gets +2/+2 until end of turn. Untap it.