msem-instigator

Flying
When Soli's Blessed enters, judge another target creature you control. (Honor it by putting a +1/+1 counter on it or condemn it by sacrificing it to draw a card.)

Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.
{3}{W}{U}: Tap target creature and put a +1/+1 counter on Solitary Guardian.

Whenever Solvent Tide attacks, create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)

When Something in the Woods enters or at the beginning of your upkeep, Something in the Woods explores. If it explores a creature card, you may have it become a copy of that card. (It loses this ability. To explore, 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 this, then you may put that card into your graveyard.)

Enchant permanent
Enchanted permanent is a land with “{T}: Add {G}{W}{U}” and loses all other card types and abilities.
{1}, Discard Song of Shoals: Add one mana of any color. Scry 1.

Defender, reach
When Soothevine Elemental enters, draw a card.

[+1]: Draw a card. Each player loses 1 life.
[–2]: Create two 1/1 black Bat creature tokens with flying and lifelink.
[–3]: Target creature gets -13/-13 until end of turn. You control abilities of that creature that trigger this turn.

Target creature gets -3/-3 until end of turn. You gain 3 life.

Tap two untapped creatures you control: Harmonize. (Trigger up to one harmony of one permanent you control.)
Harmony — Choose one —
• Soul of New Alores becomes a creature in addition to its other types until end of turn.
• Put two +1/+1 counters on target permanent.

At the beginning of each end step, if you gained life this turn, put a +1/+1 counter on a creature you control.

Destroy target creature. Then if you control a Wizard, that creature's controller loses 1 life for each creature card in their graveyard.

Put a +1/+1 counter on each creature you control. (Then exile this card. You may cast the creature later from exile.)

All creatures get -2/-2 until end of turn. At the beginning of the next end step, if three or more creatures died this turn, create two tapped Treasure tokens.

Exile target creature. That creature's controller reveals cards from the top of their library until they reveal a creature card. That player puts that card onto the battlefield, then shuffles the rest into their library.

Menace
When Spaceship Invader enters, destroy target creature you don't control with mana value 3 or less.

Primal {2}{R} (During your turn, you may cast this spell for {2}{R} instead of playing a land.)
Target creature gets +2/+0 and gains double strike until end of turn.

Look at the bottom two cards of your library. Manifest one of them, then put the other on the top or bottom of your library. (To manifest a card, put it onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)

Flying, haste
Whenever Spawn of Hadak attacks, draw a card, then discard a card.

Flying
When Spawn of Keranos enters, you may draw a card. If you do, discard a card unless you control another creature with flying.

Menace
Whenever you cast a cryptic spell, you may return target creature card from your graveyard to your hand. (Artifacts, enchantments and modal spells are cryptic.)

Haste
When Speaker of the Iris enters, abound. (To abound, you may cast a spell that costs less than this from your hand without paying its mana cost.)
Other creatures you control have haste.

Trample
Morph {3}{G}{G} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)
When you turn Spearhead Ophan face up, creatures you control get +2/+2 and gain trample until end of turn.

Rouse 4. Sacrifice a creature at the beginning of the next end step. (Distribute four +1/+1 counters among permanents you control. If they aren't creatures, tap them and they become 0/0 creatures in addition to their other types.)

Put target creature on top of its owner's library.
Agonize (You may cast this card from your graveyard by putting a -1/-1 counter on a creature you control in addition to paying its other costs. Then exile this card.)

Flash
Flying
When Spectrum Archmage enters, return target spell to its owner's hand, then abound. (To abound, you may cast a spell that costs less than this from your hand without paying its mana cost.)