msem-instigator

Other creatures you control get +1/+1.
When Kotis, Promised General dies, you may return it to its owner's hand.

Whenever you gain life for the first time each turn, create a 1/1 white Cleric creature token.

Flash
Flying
When Justiciar Overseer enters, the next 2 damage that a source of your choice would deal to you and/or permanents you control this turn is dealt to any target instead.

Exile up to one target nonland permanent you control and up to one target nonland permanent card with mana value 3 or less from your graveyard. Then return the exiled cards to the battlefield tapped under their owner's control.

Enchant creature
Enchanted creature gets +1/+1, has flying and lifelink, and is a legendary artifact in addition to its other types.

Lifelink
When Hyctaleon's Vanguard enters, look at the top six cards of your library. You may put a Soldier card with lesser mana value from among them onto the battlefield. Put the rest on the bottom of your library in a random order.
Other Soldiers you control get +1/+1.

Herald of the Yaoguai has indestructible as long as two or more creatures you control entered this turn.

Whenever you cast a legendary spell or play a legendary land, put a +1/+1 counter on Henros, Royal Herald and you gain 1 life.
{2}{W}: Look at the top six cards of your library. You may exile a legendary card from among them. Then shuffle. If the exiled card has mana value less than Henros's power, you may put it onto the battlefield tapped. If you don't, put it into your hand.

Whenever Fox of the Mushroom Forest enters or deals combat damage to a player, its activated abilities cost {W} less to activate until your next turn.
{W}, Sacrifice Fox of the Mushroom Forest: Counter target noncreature spell unless its controller pays {2}.

Whenever one or more other creatures you control enter, you gain 1 life. If at least one of those creatures was a Cleric, you gain 2 life instead.
As long as you have at least 8 life more than your starting life total, other Clerics you control get +1/+1.

When Escorted Ambassador enters, create two 1/1 white Robot Soldier artifact creature tokens.
Whenever a nonland, nontoken permanent enters, exile it unless it was the first to enter under its controller's control this turn.

Whenever a Soldier or Knight you control enters, you may sacrifice Ceanne's Dawnbringer. If you do, put your choice of two different counters on that creature from among +1/+1, first strike, lifelink, and vigilance.

At the beginning of your end step, create a 1/1 white Soldier creature token.

Changeling (This card is every creature type.)
{1}: Another target creature you control gains the creature type of your choice until end of turn.
{1}: Change the text of another target creature you control by replacing all instances of one creature type with the creature type of your choice until end of turn.

Haste
Battle cry (Whenever this creature attacks, each other attacking creature gets +1/+0 until end of turn.)
Whenever Goblin War Chariot becomes crewed, untap each creature that crewed it with mana value 1 or less. This ability triggers only once each turn.
Crew 3

Whenever Witchfinder Artur enters or attacks, each opponent mills two cards and loses 2 life.
Whenever you cast an instant or sorcery spell, you may exile target instant or sorcery card with mana value less than that spell's mana value from an opponent's graveyard. If you do, cast a copy of the exiled card without paying its mana cost.

[+1]: Augur. (Look at the top card of your library. You may sacrifice a creature to put it into your hand. Otherwise, put it back or put it into your graveyard.)
[–X]: Exile target card in your graveyard with mana value X. Copy it. You may cast the copy without paying its mana cost.
[–6]: You get an emblem with “Whenever a creature you control dies, search your library for a creature card, reveal it, and put it into your hand, then shuffle.”

Wildcast — When Ivier, Soul of the Woods enters, return target monocolored creature card from your graveyard to your hand. If mana from a nonland source was spent to cast Ivier, return that card to the battlefield instead.

This spell can't be countered.
Flying
When Aunor, Dragonsire or another Dragon you control enters, untap target land. That land becomes a 5/5 Dragon creature with flying and haste in addition to its other types.

Untap all other Elves you control during each other player's untap step.
You may cast spells as though they had flash.

{X}, {T}, Sacrifice an artifact: Exile target artifact card in your graveyard with mana value X. Create a token that's a copy of it. Activate only as a sorcery.

Indestructible
As long as your devotion to black and green is less than seven, Pharika isn't a creature.
At the beginning of your upkeep, create a 1/1 green Snake creature token. If Pharika is a creature, create a 1/1 black Snake creature token with deathtouch instead.

At the beginning of each player's upkeep, sacrifice Hayuan, the Misjudged if that player controls a creature with power 2 or less.
When Hayuan dies, create X Idol tokens, where X is the number of creatures you control. (They're artifacts with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)

If you would draw your first card each turn, instead draw two cards, then discard a card.
Whenever you draw an even numbered card in a turn, put a +1/+1 counter on Saraf, Tuned Disciple. (The second, fourth, sixth, etc.)

[+2]: Scry 2, then you may draw a card. If you don't, Liactru Stormheart deals 2 damage to any target.
[–4]: Create a 4/4 blue and red Elemental creature token. It gains flying, vigilance, and haste until end of turn.
[–10]: For each player, create a token that's a copy of target permanent that player controls. You get an emblem with “Permanents you control have hexproof.”