msem-instigator

When Cosmonaut Pioneer enters or leaves the battlefield, choose one—
• Scry 1, then draw a card.
• Create a 3/3 green Alien creature token with trample.
• You gain 5 life.

Erratic (When this creature dies, reveal the top four cards of your library. Put a creature card that costs less than this revealed this way onto the battlefield and the rest on the bottom of your library in any order.)
Whenever a creature you control enters, if you didn't cast it from your hand, target land you control becomes a 7/1 red Elemental creature with trample and haste. It's still a land.

Alpha (You may have this creature enter with a +1/+1 counter on it. If you do, it becomes alpha and can only attack alone.)
Flying
{2}{W}: Prevent all damage that would be dealt to and dealt by creatures with counters on them this turn.

When Cou Ling enters, create two 2/1 red and white Fox creature tokens.
Whenever a Fox you control deals combat damage to a player, draw a card, then you may cast an instant or sorcery card with mana value less than or equal to the damage dealt from your hand without paying its mana cost.

Sacrifice a creature: Each opponent loses 1 life and you gain 1 life.
Sacrifice two creatures: Draw a card.
Sacrifice three creatures: Exile target creature or planeswalker.

Flying
Whenever a creature you control that isn't enchanted dies, adjudicate.
Whenever an enchanted creature you control dies, return it to the battlefield at the beginning of the next end step.

Purge, then you may tap an untapped creature you control. If you do, purge again. (To purge, exile two cards that share a type from graveyards. If you do, draw a card.)

For any number of target spells or abilities your opponents control, counter it unless its controller pays {4}.

Equipped creature gets +2/+1.
Whenever equipped creature becomes the target of a spell or ability for the first time each turn, counter that spell or ability.
Equip {2}

Counter target spell.
Surveil 1.

Reveal the top five cards of your library. For each card type, you may put a card of that type revealed this way into your hand. Put the rest into your graveyard. Then you may cast a nonland card with mana value 3 or less from your hand without paying its mana cost.

Enchant creature
Enchanted creature gets +2/+2 and has “Whenever this creature attacks, tap target creature defending player controls.”

Flash
Enchant creature
Enchanted creature gets +3/+3.

Flying
When Courier Eagle enters, target creature gets +2/+1 until end of turn.

Gain control of target artifact or creature until end of turn, then untap it. It gains haste until end of turn. You may spend mana as though it were mana of any type to pay the costs of its abilities this turn.

Whenever another creature with power 2 or less you control enters for the first time each turn, you may pay {W}. If you do, draw a card.

Adorned — Coven Adherent has indestructible as long as it's equipped and/or enchanted.

When Covert Reinforcement enters, exile target nonland permanent an opponent controls until Covert Reinforcement leaves the battlefield.

{T}: Add one mana of any color.
{3}, {T}, Sacrifice Coveted Heirloom: Draw a card.
Tap three untapped artifacts you control: Return Coveted Heirloom from your graveyard to the battlefield.

Enchant creature or planeswalker
Enchanted permanent can't attack or block and loses all abilities.

You mill two cards, draw two cards, lose 2 life, and create two Treasure tokens. (They're artifacts with “{T}: Sacrifice this permanent: Add one mana of any color.”)

Choose two —
• Create a 6/6 blue Kraken creature token.
• Take an extra turn after this one.
• End the turn.
Exile Crack in Time.

This spell has flash as long as you control a permanent with flash.
Put target nonland permanent on top of its owner's library.

For each creature you control, create a token that's a copy of it. They gain haste. Sacrifice them at the beginning of the next end step.