msem-instigator

Whenever a creature enters without counters during your next turn, you may put two +1/+1 counters on it. (Then exile this card. You may cast the creature later from exile.)

When Snarling Devil enters, create four 1/1 black Possum Dog creature tokens.
At the beginning of each upkeep, put your choice of a +1/+1, lifelink, menace, trample, or vigilance counter on a token creature you control.

Destroy target nonland permanent. If it had flying, put a flying counter on a creature you control. Do the same for first strike, double strike, deathtouch, haste, hexproof, indestructible, lifelink, menace, reach, trample, and vigilance.

Whenever Thundering Towershell attacks, return a creature card with mana value 5 or less from a graveyard to the battlefield under your control. Trigger a death knell of that creature.

When Tinker Tantrum enters and at the beginning of your upkeep, you may sacrifice an artifact. If you do, reveal cards from the top of your library until you reveal an artifact card with mana value X or less, where X is 1 plus the sacrificed artifact's mana value. Put that card onto the battlefield and the rest on the bottom of your library in a random order.

You may put cards with mana value 2 or less that permanents you control explore into your hand as though they were lands. (You won't get the counter if you do.)
Whenever Torch of Those Underfoot attacks, it explores. (Reveal the top card of your library. Put it into your hand if it's a land. Otherwise, put a +1/+1 counter on this creature, then you may put that card in your graveyard.)

Whenever Tortle Veteran or another Turtle you control enters, that creature 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 this creature, then put the card back or put it into your graveyard.)

Flash
Death knell — Put a +1/+1 counter on each creature you control. (As a creature you control dies, trigger one death knell of that creature or another permanent you control.)

Whenever Valinov Collector or another artifact you control enters, Valinov Collector deals 2 damage to each opponent and you gain 2 life.

Advance {3}{R}{W}{B} (Cast this for {3}{R}{W}{B} to advance it as it enters. {3}{R}{W}{B}: Advance this as a sorcery.)
Whenever Valinov Vandal advances, target opponent sacrifices a permanent. Put a +1/+1 counter on Valinov Vandal.

Whenever Aukashi, Electric Legacy enters or equipped creature dies, attach Aukashi to a creature you control.
Whenever equipped creature deals damage to a permanent or player, Aukashi deals 2 damage to that permanent or player.
Equipped creature has double strike as long as a creature you controlled died this turn.
Equip {2}

When Cryptic Waypoint enters, create a 1/1 blue Scout creature token.
{T}: Add {G}, {U}, or {R}.

When Dedicated Waypoint enters, create a 1/1 white Scout creature token.
{T}: Add {R}, {W}, or {B}.

Whenever you make first contact, put a patch counter on Distraction Doll. (You make first contact the first time each turn you cast a spell with a name not in your graveyard or control already.)
{T}: Exile Distraction Doll and target creature with mana value less than or equal to the number of patch counters on it.

When Gleaming Waypoint enters, create a 1/1 red Scout creature token.
{T}: Add {U}, {R}, or {W}.

When Gloomy Waypoint enters, create a 1/1 black Scout creature token.
{T}: Add {W}, {B}, or {G}.

Advance {2} (Cast this for {2} to advance it as it enters. {2}: Advance this as a sorcery.)
Equipped creature gets +X/+0 and has flying, where X is the number of times it and Jet Pack have advanced this turn.
Equip {1}

Advance {2} (Cast this for {2} to advance it as it enters. {2}: Advance this as a sorcery.)
Equipped creature gets +1/+1 for each artifact you control.
Equipped creature must be blocked by an additional creature for each time it and this artifact have advanced this turn to be blocked.
Equip {3}

Exile two cards from your graveyard: Petrified Guard becomes a 3/1 Zombie creature until end of turn.

When Prophetic Prism enters, draw a card.
{1}, {T}: Add one mana of any color.

Flash
{1}, {T}: Scry 1.

Advance {3} (Cast this for {3} to advance it as it enters. {3}: Advance this as a sorcery.)
Whenever Wastes Scrambler advances, put your choice of a +1/+1, first strike, menace, trample, or vigilance counter on it. If {R}{W}{B} was spent to advance it, repeat this process twice.
Crew 1

When Wild Waypoint enters, create a 1/1 green Scout creature token.
{T}: Add {B}, {G}, or {U}.

({T}: Add {U}, {R}, or {W}.)
Ancient Dominion enters tapped.

Barbed Reef enters tapped. When it does, 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 this, then you may put that card into your graveyard.)
{T}: Add {B}.
{4}{B}: Barbed Reef becomes a Jellyfish creature. (This effect lasts indefinitely.)