msem-instigator

Flash
{1}{W}: Return Nimble Explorer to its owner's hand.

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.

Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)
As long as you control three or more artifacts, Regal Seasnake has vigilance. (Attacking doesn't cause it to tap.)

Flying
Legendary spells you cast cost {1} less to cast.
{W}{U}{B}{R}{G}: Search your library or graveyard for a legendary card, reveal that card, and put it into your hand. If you searched your library this way, shuffle.

Unceasing Flames deals X damage to any target, where X is 2 plus the number of cards named Unceasing Flames in your graveyard.
Conjure three cards named Unceasing Flames and shuffle them into your main library.

Wu Xing (Add effects based on the number of colors of mana spent to cast this spell.)
1 | When you next cast an instant or sorcery spell this turn, copy it. You may choose new targets for the copy.
3 | When you cast your next creature spell this turn, copy it.

As an additional cost to cast this spell, discard a card at random.
Draw three cards.

Sacrifice another creature: Grisly Rougarou deals damage equal to the sacrificed creature's power to any target.

Flash
If a card or token would be put into an opponent's graveyard from anywhere, exile it instead.

Enchant creature or land
Whenever enchanted permanent becomes tapped for the first time each turn, it explores. (Reveal the top card of your library. Put that card into your hand if it's a land. Otherwise, put a +1/+1 counter on that creature, then put the card back or put it into your graveyard.)

When this creature enters, look at target opponent's hand. You may exile a nonland card from it. For as long as that card remains exiled, its owner may play it. A spell cast this way costs {2} more to cast.
Arise {2}{W}{W} ({2}{W}{W}, Exile this from your graveyard as a sorcery: Create a black token copy of it that's also a Zombie and can't block.)

Trample
Cadence (Whenever you cast a spell, if its mana value is greater than this creature's power, put a +1/+1 counter on this creature.)

Whenever Yri, the Daring Blade and exactly one other creature attack, Yri and that creature can't be blocked by creatures with mana value 3 or less this turn.

Vigilance
When Traveling Duo enters, create a 1/1 colorless Servo artifact creature token.

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

When Ikari-no-Oni enters, other creatures you control get +1/+0 until end of turn.

Whenever Sanctuary is dealt damage, you gain that much life.
All damage that would be dealt to another creature you control is dealt to Sanctuary instead.

Whenever Hedge Dashers attacks, if you control a permanent with a counter on it, Hedge Dashers gets +1/+1 and gains trample until end of turn.

Return target creature card with mana value 3 or less from your graveyard to the battlefield.
Fabled {4}{W}{W} (Then if you cast this for its fabled cost, put it onto the battlefield transformed attached to that creature.)

When this creature enters, create two 1/1 white Peasant creature tokens.
Whenever this creature attacks, you may pay {4}{G/W}. If you do, attacking Citizens and Peasants get +1/+1 until end of turn.

Reach
Canopy Scout gets +1/+0 for each land card in your graveyard.

Shepherd of the People can't be blocked by creatures with power 2 or less.
Whenever another Citizen or Peasant you control enters, Shepherd of the People gets +1/+1 until end of turn.

Counter target monocolored spell.

Whenever an artifact you control is put into a graveyard from the battlefield, create a 4/4 red Dragon creature token with flying.

Haste
Art of war — At the beginning of your end step, if Teikoku Skirmisher dealt damage to an opponent this turn, put a +1/+1 counter on it.