msem-instigator

Fardancer Liege's power and toughness are each equal to the number of colors of mana that lands you control could produce.

Forestheart Elemental enters with a +1/+1 counter on it for each land you control.

Frilled Hydra enters with X +1/+1 counters on it.
Defiance (Whenever this creature takes damage, if it survives and wasn't defiant, put a +1/+1 counter on it and it becomes defiant.)
Frilled Hydra has hexproof as long as it's defiant.

Trample
Gloamrazer Hydra enters with four +1/+1 counters on it.
Whenever a nontoken creature you control dies, if it was embattled, create an X/X green Hydra creature token, where X is that creature's power. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)

Archive 6
Grohl's Study's power and toughness are each equal to the number of cards in the archived library.
Whenever Grohl's Study deals combat damage to a player, you may put a card from the archived library into your hand.

Horizon Wayfarer's power and toughness are each equal to the number of differently named lands you control.

Transcend (Activate as a sorcery to gain the next type and a +1/+1 counter.)
Jutou enters with X +1/+1 counters on her.
{3}{G}: Demigod — You gain life equal to the greatest power among creatures you control.
{6}{G}: God — Search your library for a creature card with the same power as a creature you control, put it onto the battlefield, then shuffle.

Mistwake Hydra enters with X +1/+1 counters on it.
Creatures with power less than Mistwake Hydra's power can't block it.

Okrophore's power and toughness are each equal to the number of colorless cards in your graveyard.

Pelagic Hydra enters with seven +1/+1 counters on it.
{1}{G}: Put a +1/+1 counter on Pelagic Hydra.
Remove a +1/+1 counter from Pelagic Hydra: It deals 1 damage to target creature blocking or blocked by it.

Trample
Qiyan enters with twice X +1/+1 counters on them.
If damage would be dealt to Qiyan while they have a +1/+1 counter on them, prevent that damage, remove that many +1/+1 counters from Qiyan, then create a 0/0 green Hydra creature token and put twice that many +1/+1 counters on it.

Ravenous Hydra enters with X +1/+1 counters on it.
Whenever Ravenous Hydra deals combat damage, proliferate. (You choose any number of permanents and/or players with counters on them, then give each another kind of a counter already there.)

When Renatured Vines enters, draw a card and create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)
Renatured Vines power and toughness are each equal to the number of cards in your hand.

Trample
Rift Prowler enters with X +1/+1 counters on it, where X is your fealty to Forests. (Each Forest you control counts towards your fealty to Forests.)

Trample
Savage Mammoth gets +1/+1 for each land you control.
Ride {4}{G} ({4}{G}: Transform this and attach it to target creature you control without a Steed. Ride only as a sorcery.)

Scion of the Wild's power and toughness are each equal to the number of creatures you control.

Pressure {2}{G}{G} (You may cast this spell for its pressure cost if there are seven or more cards in your graveyard.)
Trample, hexproof
Shambling Dreadreef's power and toughness are each equal to the total number of land cards you own on the battlefield and in your graveyard.

Shambling Hive power and toughness are each equal to the number of Insects you control.
Shambling Hive has vigilance as long as you control four or more Insects, and has trample as long as you control eight or more Insects.

Vigilance
Shuye, Forever Watching's power and toughness are each equal to the number of noncreature permanents you don't control.

Soulraving Hunt's power and toughness are each equal to the number of lands you control.
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

Spawn of Andazir enters with X +1/+1
counters on it.
Lionize {2}{G} ({2}{G}, Exile this card from your hand:
Put a +1/+1 counter on target creature and it gains the following ability until end of turn. You may cast this card on a later turn from exile.)
Whenever this creature deals damage to a player or noncreature permanent, double the number of +1/+1
counters on it.

Swarm of Sporemites gets +1/+1 for each creature card and Revelation card in your graveyard.

Tarmovore's power and toughness are each equal to twice the number of card types among cards in all graveyards.

Enspirit (As you cast this spell, you may exile a nonenchantment creature you control until this leaves the battlefield or fails to resolve. Reduce this spell's cost by the exiled card's mana value.)
Tenacious Brawler enters with X +1/+1 counters on it.

Terra Novea's power and toughness are each equal to the number of permanents you control.
{T}: Add {G} for each land you control.