msem-instigator

As an additional cost to cast this spell, sacrifice a creature.
Destroy target creature.

Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)
Whenever you cast an enchantment, instant, or sorcery spell, Noble Barracuda gets +1/+0 until end of turn. Scry 1.

Discard your hand. Draw cards equal to the number of creatures that died this turn.

Target creature you control gets +X/+X until end of turn, where X is the number of +1/+1 counters among creatures you control.

Flash
As long as Iroshi entered this turn, you may activate their loyalty abilities any time you could cast an instant.
[+1]: You may return a creature you control to its owner's hand. If you do, draw a card.
[–1]: Create a 2/2 green Ninja creature token.
[–2]: Target creature you control deals damage equal to its power to target creature or planeswalker.

Choose target attacking or blocking creature. Scry 3, then reveal the top card of your library. Judge Unworthy deals damage equal to that card's mana value to that creature.

When Marauder's Broadsword enters, you may pay {1}. If you do, create a 1/1 white Soldier creature token and attach Marauder's Broadsword to it.
Equipped creature gets +2/+0.
Equip {2}

Distorted (This creature can be blocked by tapped creatures but not untapped creatures.)
{1}{G}: Untap Chantwood Guards.

Assault {2}{R} (Whenever this attacks, if it has no +1/+1 counters on it, you may pay its assault cost to put a +1/+1 counter on it.)
When Monstrous Hila assaults, it deals 3 damage to any target.

{T}: Add {C}.
{T}, Pay 1 life: Add {B}.
{5}{B}, {T}, Sacrifice Collapsing Ridges: Return target creature card from a graveyard to the battlefield under your control. Activate only as a sorcery.

Creatures you control have trample, haste, and hexproof.
{2}{G}{G}: Create a 2/2 white Cat creature token.

Play with the top card of your library revealed.
Spells you cast that share a creature type with the top card of your library cost {1} less to cast.

Whenever you discard one or more cards, create a Treasure token and draw a card. This ability triggers only once each turn.
Whenever two or more creatures you control attack, you may discard a card. If you do, target creature can't block this turn.

Tumblewalker has vigilance as long as you control another Scarecrow.

Whenever you cast a spell from your graveyard, you may return target nonland permanent to its owner's hand.
Sacrifice a Clue: Return Trespasser of the Gallows from your graveyard to your hand.

Soldiercycling {1}{W}, Wizardcycling {1}{U}, Zombiecycling {1}{B}, Warriorcycling {1}{R}, Elfcycling {1}{G} ({1}{G}, Discard this card: Search your library for an Elf card, reveal it, and put it into your hand, then shuffle.)
Sentinel of Latter Days is every creature type as long as it's in your library.

Haste
Frenzy 2 (Whenever this creature attacks and isn't blocked, it gets +2/+0 until end of turn.)

Menace
Pay 2 life: Investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)
Sacrifice a permanent: Darna gets +1/+1 until end of turn.

{B}, Pay 1 life: Target creature's controller sacrifices it unless that player pays 1 life.
{B}, Sacrifice a creature: You gain life equal to the sacrificed creature's power.

{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast enchantment spells or to activate an ability of an enchantment.
When Bastion, Node of the Free is destroyed, return it to its owner's hand.

This spell costs {U} less to cast if you dealt combat damage to a player this turn with a Rogue.
Flying
When Balloon Voyager enters, draw a card.

When Pantheon Breaker enters, each opponent sacrifices an enchantment.

When Dawn Silhouette enters, you may exile target creature not named Dawn Silhouette you control. Return that card to the battlefield under your control at the beginning of the next end step.
Mirage {1}{W} (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.)