msem-instigator

Enchant creature
Enchanted creature can't attack or block, and its activated abilities can't be activated.
Mirage {W/U} (You may cast this spell as though it had flash for its mirage cost. If you do, sacrifice it at the beginning of the next cleanup step.)

Double the power and toughness of target creature you control until end of turn. It doesn't untap during its controller's next untap step.

Rhapsody {4}{R}{R} (Pay {4}{R}{R} to cast this as a 4/4, or as a sorcery to make it become a 4/4.)
Double strike

Create two 1/1 white Soldier creature tokens. You gain 4 life.

Creatures you control get +2/+1 until end of turn. Citizens and Peasants you control gain first strike until end of turn.
Foretell {1}{W} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Infamy 1 (Whenever this creature deals combat damage to a player, if it has no +1/+1 counters on it, put a +1/+1 counter on it and it becomes infamous.)
When Alpha Scout becomes infamous, create a 2/2 green Wolf creature token.

Rotrider Renegade can't block or be blocked.
{1}{B}: Rotrider Renegade gets +1/+1 until end of turn.
Dash—Reveal a Rogue card from your hand, Pay 2 life (You may cast this spell for its dash cost. If you do, it gains haste, and it's returned from the battlefield to its owner's hand at the beginning of the next end step.)

Johanna, Skarvith Marshal has first strike as long as it's attacking.
Whenever you attack, you may pay {X}{R/W}{R/W}. When you do, put a +1/+1 counter on each of up to X target attacking creatures. Those creatures gain first strike until end of turn.

At the beginning of your upkeep, discard a card and create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)

When Manglehorn Hunter enters, draw a card and you lose 1 life.

Deathtouch
Invocation — Whenever you spend four or more mana to cast a spell or activate an ability during your turn, untap Killer Scorpion.

Whenever you discard a card, tap up to one target creature.

When Maghbri Whisper enters, nourish 1. (To nourish 1, either put a +1/+1 counter on this creature or create a 1/1 white Citizen creature token.)
Sacrifice a creature: Maghbri Whisper gets +2/+2 until end of turn.

Lifelink, haste
Wanton Cleaver has first strike as long as it's attacking.

Dreamscaper enters tapped with three stun counters on it. (If it would become untapped, remove a stun counter from it instead.)
Whenever you cast your second spell each turn, you may untap Dreamscaper or tap target creature.
Whenever Dreamscaper deals combat damage to a player, draw two cards.

Starting with you, each player either passes or reveals the top card of their library. Each player that revealed a card this way pays life equal to its mana value. If a player can't, that player passes. Then each player who hasn't passed yet puts that card into their hand. Repeat this process until each player has passed.

Bloodprice {B}{B}{B}{B} (You may cast this card by sacrificing a creature and paying its bloodprice.)
Lifelink, haste
Sacrifice another Demon: Jejun, Dark Hunter gains flying and indestructible until end of turn.

Create a token that's a copy of target creature, except its power and toughness are switched. Sacrifice that token at the beginning of your next end step.

{T}, Sacrifice Skeletal Oasis: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

{T}, Pay 1 life: Add {W} or {B}.
{1}, {T}, Sacrifice Legitimate Establishment: Investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

Lifelink
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.)

Target creature you control fights another target creature. (Each deals damage equal to its power to the other.)

Harvest (You may tap any number of creatures you control as you cast this spell. If you do, reduce this spell's mana cost by their total power.)
Target creature you control deals damage equal to its power to target creature you don't control.

Forebode three times, then untap each Omen you control. Until end of turn, if you would draw a card while your library has no cards in it, you win the game instead. (Create three tapped colorless Omen artifact tokens with “{T}, Discard a card, Sacrifice this artifact: Draw a card.”)

Survivors you control have flying.