msem-instigator

Trample
Whenever another Dwarf you control enters, create a colorless artifact token named Ale. It has “{T}, Sacrifice this artifact: Target creature gets +2/+0 until end of turn. Activate only as a sorcery.”

When Mana Potion enters, scry 1, then draw a card.
{2}, {T}, Sacrifice Mana Potion: Add two mana of any one color.

When Night Howlers enters, target opponent reveals three cards from their hand and you choose one of them. Exile that card until Night Howlers leaves the battlefield.

Whenever you cast a noncreature spell, you may pay {R}. If you do, untap Kamito Rageweaver.
{T}: Kamito Rageweaver deals 1 damage to target player.

Whenever a player cycles a card, that player mills two cards.

Trample
Whenever another nontoken creature you control dies, you may return it to the battlefield. It becomes an Aura enchantment with enchant creature you control and “Enchanted creature gets +X/+X, where X is this Aura's mana value.”

Flying
Menagerie — When Bleakrealm Mini-Menace enters, if there are five or more creature types among creatures you control, it deals 2 damage to target opponent and 2 damage to up to one target creature or planeswalker that player controls.

When Howler Sellout enters, for each creature that died this turn, post a bounty on up to one target creature an opponent controls. (Put a bounty counter on that creature. It has “When this creature dies, each opponent draws a card” as long as it has a bounty counter on it.)

Return target creature card from your graveyard to the battlefield. It has base power and toughness 1/1 and is a Construct in addition to its other types. (This effect lasts indefinitely.)
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.”)

Whenever Queen Hannaru enters or attacks, put a +1/+1 counter on another target creature you control.
At the beginning of your upkeep, if there are four or more +1/+1 counters among creatures you control, you may transform Queen Hannaru.

Flying, haste
{X}{R}{R}, Exile an instant or sorcery card with mana value X from your graveyard: Return Merkurio's Familiar from your graveyard to the battlefield. It gets +X/+0 until end of turn.

Other Dryad creatures you control get +1/+1 and have hexproof.

When Artificial Wayfinder enters, you may search your library for a basic land card, reveal it, put it into your hand, then shuffle.

Blazing Exultation deals 3 damage to any target.
{2}{R}: Shuffle Blazing Exultation and up to one other instant or sorcery card from your graveyard into your library.

When Benthic Tidebreaker enters, reveal the top card of each player's library and exile one of those cards. You may play that card for as long as it remains exiled, and you may spend blue mana as though it were mana of any color to cast it.
Evoke {1}{U} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Target spell's controller manifests it. (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.)

Crumbling Vestige enters tapped.
When Crumbling Vestige enters, add one mana of any color.
{T}: Add {C}.

({T}: Add {B}.)
Forgotten Pit enters tapped.
Deathtouch
{2}{B}{B}: Forgotten Pit becomes a creature in addition to its other types until end of turn.

Sunrise River enters tapped.
{T}: Add {U}.
You may untap Sunrise River during each other player's untap step. Whenever you do, you lose 1 life.

Players can't sacrifice creatures to cast spells or activate abilities unless that player sacrifices an additional creature. The same is true for discarding cards and paying life.

Target player mills six cards. Return each creature that shares a name with a card milled this way to its owner's hand.
Prophecy {1}{U} (Once each turn, you may exile a card with prophecy as you reveal it. When you do, you may cast it for its prophecy cost as long as it's exiled.)

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.)

{1}, {T}: Exile target creature you control until Elsewhere Mirror leaves the battlefield. (It returns to the battlefield under its owner's control.)
{3}: Choose a permanent card exiled with Elsewhere Mirror. Target creature becomes a copy of that card until end of turn.

Look at target opponent's hand, then fateseal 1. (To fateseal 1, look at the top card of an opponent's library, then you may put it on the bottom of that player's library.)