msem-instigator

{1}{G}: Night's Guard gets +2/+2 until end of turn. Activate only once each turn.

Flash
Flying
Whenever a player discards a card, you draw a card. This ability triggers only once each turn.

At the beginning of your upkeep, if Nightmare Riders is in your graveyard, you may mill two cards.

{B}, Discard a card: Post a bounty on target creature. (Put a bounty counter on that creature. It has “When this creature dies, each opponent draws a card” as long as it has a bounty counter on it.)

Flying
At the beginning of your upkeep, mill seven cards, then you may cast an instant or sorcery card from your graveyard. If that spell would be put into your graveyard, exile it instead.
If you would draw a card while your library has no cards in it, you win the game instead.

First strike
Crew 1 (Tap any number of creatures you control with total power 1 or greater: This Vehicle becomes an artifact creature until end of turn.)

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
When Nizev Brawler enters, target creature can't block this turn.

Whenever No-Good Gunpointer attacks, you may pay 3 life. If you do, draw a card.

Other creatures you control get +1/+1.
As long as Nobility is in your graveyard and you control a white enchantment, creatures you control get +1/+1.

When Noble Pridelord enters, creatures you control get +1/+1 until end of turn.

Trample
Ride {3}{G} ({3}{G}: Transform this and attach it to target creature you control without a Steed. Ride only as a sorcery.)

As long as it's not your turn, Northrime Amalgam gets -2/+2.

Flying

Survivors you control have haste.

Chronicle (As this enters and after your draw step, add a lore counter. Stop after III.)
[Lore I-II] Target creature you control can't be blocked by creatures with power 2 or less this turn.
[Lore III] Draw a card.

Chronicle (As this enters and after your draw step, add a lore counter. Stop after III.)
[Lore I-II] Tap target creature you don't control.
[Lore III] Tap target creature you don't control. It doesn't untap during its controller's next untap step.

Trample
Whenever you attack with another creature with power 4 or greater, put a +1/+1 counter on OH-14 Diamond.

Menace
When OM-6 Walker dies, OM-6 Walker deals damage to each player equal to twice the number of nonbasic lands that player controls.

When Obscure Apostle enters, create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)
Whenever you sacrifice an Idol, Obscure Apostle can't be blocked this turn.

Flash
Whenever you cast an artifact or enchantment spell, put a +1/+1 counter on Observer of Secret Paths. It can't be blocked this turn.

Flying
When Obsidian Hellkite dies, it deals 2 damage to up to one target creature or planeswalker. If that creature or planeswalker would die this turn, exile it instead.
Foreshadow {4}{R}{R} (You may cast this spell for its foreshadow cost. If you do, also trigger its “dies” abilities when it enters.)

Whenever one or more artifacts you control enter, put a +1/+1 counter on Octopus Shiny-Grabber and you gain 1 life.

Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)
Concord — Once each turn, when an opponent casts a spell or activates an ability that targets a Merfolk or enchantment you control, you may counter that spell or ability if there are four or more card types among permanents you control.

Whenever you cast a spell, note its colors.
At the beginning of combat on your turn, up to X target creatures get +2/+0 and gain menace until end of turn, where X is the number of colors noted with Off-Set Rumormonger.

Flying
Menagerie — When Old-Rune Watcher enters, if there are five or more creature types among creatures you control, draw a card.