msem-instigator

Enchant creature
When Strength in Imagining enters, if it enchants a face-down creature, put a +1/+1 counter on that creature.
Enchanted creature has flying and trample.

Enchant creature
Enchanted creature gets +3/+0 and has first strike.

Strident Retainer's power and toughness are each equal to the number of creatures you control.
Art of war — At the beginning of your end step, if Strident Retainer dealt damage to an opponent this turn, create a 1/1 colorless Samurai creature token.

Strider Engine enters tapped and with a -1/-1 counter on it unless you spent at least three colors of mana to cast it.

Equipped creature gets +1/+1 and has haste.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Choose one —
• Destroy target creature with flying.
• Destroy target artifact.

Exile up to one target artifact or enchantment.
Coalesce {5}{G} (You may cast this from your graveyard for {5}{G}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)

Enchant creature
When Strike Fear enters, draw a card.
When enchanted creature attacks, target creature can't block this turn.

You may have Strikebreaker enter as a copy of a non-Aura enchantment you control, except it's a 2/2 Construct Actor creature in addition to its types.

Striptide deals 1 damage to target creature. Unattach all artifacts from it. It becomes red until end of turn.
Draw a card.

Transformed creatures you control get +2/+2.

Flying
Whenever you cast a noncreature spell, note its mana value.
When Strix of Dark Omens dies, draw a card and create a 1/1 blue Bird creature token with flying for each different number noted with it.

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn.

Whenever this creature attacks, up to two target Citizens or Peasants each get +1/+0 and gain trample until end of turn.

Bulwark — {2}{G}: Stronghold Recruit gets +2/+2 until end of turn. Activate only once each turn and only if you control a creature with toughness 4 or greater.

Flash
Enchant creature
Enchanted creature gets +1/+1 and has “Whenever this creature deals combat damage to an opponent, draw a card.”

Players can cast spells only during their own turns.
Each player can't cast more than one spell each turn.

Prowess
Art of war — At the beginning of your end step, if Student of Shigure dealt damage to an opponent this turn, you may draw a card, then discard a card.

Whenever Student of Winds attacks, upgrade target attacking creature. (Give it one of the listed counters it doesn't already have.)
• +1/+1
• Flying

When Student of the Crane enters, create a 1/1 white Bird creature token with flying.

When Student of the Scroll enters, scry 2.

Improve {G} ({G}: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)
Whenever an Elf you control dies, you may search your library for a land card, reveal it, put it into your hand, then shuffle.

Investigate ten times. (Create ten colorless Clue artifact tokens with “{2}, Sacrifice this artifact: Draw a card.”)

Reveal the top four cards of your library. You may put one into your hand and the rest into your graveyard.
Compose (Then if you cast this from your hand, exile it and create a Saga token with “r3—You may cast a copy of this card from exile without paying its mana cost.”)

Return target nonland permanent to its owner's hand. If you control an artifact, draw a card.