msem-instigator

Whenever you put a counter on another permanent you control, put a +1/+1 counter on Herald of Ruination. This ability triggers only once each turn.
Surpass {5}{G} ({5}{G}: Transform this creature. This costs {1} less to activate for each counter on it. Activate only as a sorcery.)

At the beginning of your upkeep, put a +1/+1 counter on Heyu, Immortal Hunter.
Whenever Heyu becomes the target of a spell or ability an opponent controls, counter it if Heyu has the greatest power among creatures on the battlefield.

Concord — Highland Hermit gets +1/+1 and has hexproof as long as there are four or more card types among permanents you control.

Transcend (Activate as a sorcery to gain the next type and a +1/+1 counter.)
{T}, Tap an untapped creature you control: Add one mana of any color.
{G}: Demigod — Whenever you cast a creature spell this turn, draw a card.
{4}{G}{G}: God — Creatures you control get +3/+3 and gain trample until end of turn.

{T}: Add one mana of any color. You can't spend this mana to cast spells with mana value 3 or greater.
Revive {2}{G} ({2}{G}, Exile this card from your graveyard: Create a token that's a copy of this card, except it has no mana cost. Activate this ability only any time you could cast a sorcery.)

Spells and abilities you control that target Inconspicuous Sheep cost {1} less.
As long as Inconspicuous Sheep is enchanted or equipped, they're a 3/3 legendary Sheep Rogue named Agent S.

You may play lands from graveyards.
{9}{G}{G}: Put nine +1/+1 counters on Jirada, Elder of Caulte.

Whenever you cast an instant or sorcery spell, choose a counter on target permanent or player. You may put an additional counter of that kind on that permanent or player.

{1}{G}: Keen Seafarer voyages. (If it isn't blocking or targeted by another spell or ability, it phases out.)
Whenever Keen Seafarer phases in, put a +1/+1 counter on it.

Ward {2}
Whenever one or more Auras you control enter for the first time each turn, adjudicate. (Create a white enchantment Aura token with enchant creature and “Sacrifice this token: Untap enchanted creature.” attached to target creature.)
Keeper of Secret Havens gets +1/+1 for each Aura you control.

When Kin of the Rainforest enters, you may put a land card from your hand onto the battlefield.
Ascend {1}{R} ({1}{R}: Exile this creature, then return it to the battlefield transformed. Ascend only as a sorcery.)

Landfall — Whenever a land you control enters, Landbound Connoisseur gets +1/+1 until end of turn, then you may have another target creature get +X/+X until end of turn, where X is Landbound Connoisseur's power.

When Leafguard Larva enters or a creature you control scavenges it, return target card from your graveyard to your hand.
Scavenge {3}{G} ({3}{G}, Exile this card from your graveyard: Put a number of +1/+1 counters equal to this card's power on target creature. Scavenge only as a sorcery.)

Trample
Lian Taizi gets +1/+1 for each card in your hand.
When Lian Taizi enters, return any number of target cards with different mana values from your graveyard to your hand.

When Life's Harbinger dies, you may put a +1/+1 counter on target creature you control.
{T}: Add {G}.

When Little Pig enters, if you control a land named Far-Off Lands, put two +1/+1 counters on it.

{2}{G}: Put a +1/+1 counter on Lonesome Ravager.
Ride {G} ({G}: Transform this and attach it to target creature you control without a Steed. Ride only as a sorcery.)

When Lost Kitten leaves the battlefield, create a 1/1 white Peasant creature token.

Heretic (Whenever you cast a spell that doesn't share a color with this creature, it gets +1/+1 until end of turn.)
Whenever you cast a white, blue, black, or red spell, add one mana of any color that spell isn't.

Whenever you gain life for the first time each turn, reveal the top card of your library. If it's a land or creature card, put it into your hand. Otherwise, put it into your graveyard.

Whenever you sacrifice one or more permanents, put a +1/+1 counter on Marsh Dweller.

Trample
Whenever you cast a spell with more colors than the number of counters on Martoob Beastkeeper, put a +1/+1 counter on Martoob Beastkeeper.

Flash
Reach
Whenever Mattia enters or becomes tapped, put a +1/+1 counter on target creature you control.
{2}{G}, {T}: Target creature must be blocked this turn if able. Activate only as a sorcery.

Deathtouch

When Mul Daya Elder enters, search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
Whenever a land you control enters, put a +1/+1 counter on Mul Daya Elder.