msem-instigator

You don't lose the game for drawing from an empty library.
As long as you have seven or fewer cards in each of your libraries, you may cast spells without paying their mana costs.

Whenever another creature with power 4 or greater you control enters, you may draw a card.

Vigilance, trample
At the beginning of combat on your turn, put a +1/+1 counter on target legendary creature you control.

Search target player's library for a card and exile it, then that player shuffles.
Coalesce {5}{B} (You may cast this from your graveyard for {5}{B}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)

{T}: Add {C}.
Satrapies you control have “{1}, {T}: Add one mana of any color.”

Meteorain deals 5 damage divided as you choose among any number of target creatures or planeswalkers.

Protection from sorceries
Whenever Magdel, Caller of Souls attacks, create a 1/1 white Spirit creature token with flying that's tapped and attacking for each storied permanent you control. Exile the tokens at end of combat. (Enchantments and legendary permanents are storied.)

Prevent all damage that would be dealt to target player this turn.
Fabled {1}{W}{W}{W} (Then if you cast this for its fabled cost, put it onto the battlefield transformed attached to that player.)

{T}: Add {U}. Spend this mana only to activate an ability or cast an instant or sorcery spell.

Each player sacrifices a creature.
Coalesce {5}{B} (You may cast this from your graveyard for {5}{B}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)

Take an extra turn after this one. At the beginning of that turn's end step, sacrifice each land you control. Whenever you cast a spell during that turn, copy it. You may choose new targets for the copy.
Exile Futuretheft.

Death knell — Put a +1/+1, flying, lifelink, or menace counter on Senn, the Haunting Gaze, then trigger a death knell of another permanent you control. (As a creature you control dies, trigger one death knell of that creature or another permanent you control.)

Whenever an attacking creature your team controls dies, you gain 3 life.

Whenever another creature enters, you may gain 1 life.

Lifelink
When Vel enters, choose up to one other target nonland permanent. If you gained or lost life this turn, exile that permanent until Vel leaves the battlefield.

Modular Mercenary gets +1/+0 and has first strike as long as you control a creature with a +1/+1 counter on it.

Enchant creature
When Feline Furor enters, it deals 2 damage to enchanted creature.
Enchanted creature gets +2/+0 and has menace.

{T}: Add {C}.
{3}, {T}: Put a +1/+1 counter on each Boar, Goat, Horse, Ox, and Sheep creature you control.

Destroy target creature. Create a tapped 2/2 black Zombie creature token.

Mark (Whenever this creature attacks, mark target creature until end of turn.)
Alley Hunter has lifelink as long as it's blocked by a marked creature.

Flying
Whenever Omid enters or one or more Armies you control attack, recruit. (Create a 0/0 white Soldier Army creature token, then put a +1/+1 counter on each Army you control.)

Distribute three +1/+1 counters among up to three target creatures you control. Those creatures gain first strike until end of turn.

Encourage ({T}: Another target creature you control gets +1/+1 until end of turn. Encourage only as a sorcery.)
Whenever Paladin's Attendant encourages a creature, that creature gains first strike until end of turn.

When Coincutter Fence enters, starting with you, each player may create a 2/1 red Rogue creature token with “This creature can't block.” For each opponent that does, create a Treasure token.

Attacking creatures get +2/+0 and gain trample until end of turn.