msem-instigator

At the beginning of combat on your turn, for each permanent type, aetherize up to one target permanent you control of that type. (To aetherize, create a token that's a copy of it, then exile that token.)

Flying
Whenever Haerthach, the Wight King deals combat damage to a player, you may sacrifice another creature. When you do, create a 1/1 white Spirit creature token with flying. Return the sacrificed card to the battlefield tapped and under your control at the beginning of the next end step.

Vigilance
The first instant or sorcery spell you cast each turn has conspire. (As you cast that spell, you may tap two untapped creatures you control that share a color with it. When you do, copy it and you may choose a new target for the copy.)

Trample
As an additional cost to cast creature spells, you may sacrifice a permanent. If you do, that spell costs {2} less to cast and that creature enters with an additional +1/+1 counter on it.

Hollowghast, the Iron Phantom enters with three +1/+1 counters on it.
If damage would be dealt to Hollowghast, prevent that damage. Remove a +1/+1 counter from Hollowghast.

{T}: Izahl, the Stormbringer deals 1 damage to any target.
Whenever you cast a noncreature spell, you may untap target creature you control.

Changeling (This card is every creature type.)
As Kalyn, Wildkin Envoy enters, choose up to three non-Human creature types.
Other creatures you control with one or more of the chosen types get +1/+1.
{2}, {T}: Create a 1/1 colorless Shapeshifter creature token with changeling. Activate only outside of combat.

Whenever a creature token you control deals combat damage to an opponent, it deals that much damage to each other opponent.
At the beginning of combat on your turn, you may sacrifice another creature. If you do, create a 2/2 red, white, and black Knight creature token with haste.

Abilities of creatures you activate that aren't mana abilities cost {2} less to activate. This effect can't reduce the mana in that cost to less than one mana.
{T}: Target creature gains haste until end of turn.

Prowess
Landfall — Whenever a land you control enters, create a 1/1 green, blue, and red Elf Scout creature token with prowess.

Whenever Scarhide, Arsenal Crafter attacks, create a token that's a copy of an Equipment attached to Scarhide and attach the token to Scarhide. When you can't, arm it. (Create a colorless Equipment artifact token with “Equipped creature gets +1/+0” and equip {2}, then attach it to that creature.)

Flying, trample
Whenever Skali, the Last Sunfeather attacks, abound. If a creature spell is cast this way, you may have that creature enter tapped and attacking. (To abound, you may cast a spell that costs less than this from your hand without paying its mana cost.)

Other legendary creatures you control get +1/+1.
At the beginning of your upkeep, you may search your library for a legendary card, reveal that card, and put it into your hand. If you do, you skip your draw step this turn and shuffle.

{1}, {T}, Sacrifice two or more nonland permanents: Return target creature card from your graveyard to the battlefield. If permanents with total mana value 4 or greater were sacrificed this way, draw a card.

Flying
Whenever one or more creatures you control deal combat damage to a player, exile the top card of that player's library. Until end of turn, you may play cards exiled with Zorganis, Dread Specter and you may spend mana as though it were mana of any type to cast those spells.

Indestructible
Legendary permanents you control have indestructible.

Flying
When Ageless Lorekeeper enters, you may discard your hand. When you do, draw three cards.

At the beginning of your end step, draw a card.
Whenever a creature deals combat damage to you, that creature's controller gains control of Ambition's Crown.

When Aureate Golem enters, create a Treasure token. Each other player creates a tapped Treasure token. (They're artifacts with “{T}, Sacrifice this artifact: Add one mana of any color.”)

When Awoken Animus enters, create two 1/1 colorless Shapeshifter creature tokens with changeling. (They're every creature type.)
{2}, Discard Awoken Animus: Search your library for a basic land card, reveal it, put it into your hand, then shuffle.

Flying
When Dreadstone Watcher dies, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

At the beginning of each combat, you may have Elderin, Crystalline Crusader become a copy of another target creature you control with mana value 3 or less until end of turn, except its name is still Elderin, Crystalline Crusader, it's still 3/3, still legendary, and it's an artifact in addition to its other types.
{W}{U}{B}{R}{G}: Elderin gets +3/+3 until end of turn.

{T}: Add one mana of any color.
{T}, Sacrifice Elderthrone Shard: Draw a card.

{T}: Add {C} and one mana of any color.

Flying
Improve {2} ({2}: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)
At the beginning of combat on your turn, up to two target embattled creatures gain double strike until end of turn. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)