msem-instigator

As long as an opponent has two or fewer cards in their hand, Bonespitting Monstrosity gets +2/+2 and has menace and “Whenever Bonespitting Monstrosity attacks and isn't blocked, create a 1/1 black Skeleton creature token.”

At the beginning of combat on your turn, target creature you control explores three times. It attacks this combat if able and other creatures you control can't attack this combat. (Reveal the top card of your library. Put that card into your hand if it's a land. Otherwise, put a +1/+1 counter on that creature, then put the card back or put it into your graveyard.)

Attacking creatures you control have first strike.
Whenever three or more creatures you control die, Glorysinger deals 4 damage to any target.

Vigilance
This spell costs {1} less to cast for each +1/+1 counter among creatures you control.

Each opponent loses X life and you gain X life, where X is the number of Illusions you control.
Acquiesce (If you cast this spell from your hand, exile it as it resolves. When one or more creatures you control deal combat damage to an opponent, you may cast this card from exile without paying its mana cost.)

Destroy target noncreature permanent.
Memento {5}{G}{G} (You may cast this from your graveyard for {5}{G}{G}. If you do, put it onto the battlefield transformed after it resolves. Exile it if it would leave the battlefield or not resolve.)

Flying
When Azos enters, each opponent reveals their hand. You choose any number of nonland cards in players' hands and/or creatures on the battlefield with total mana value 7 or less. Exile those cards and/or permanents.

Flash
When Stalker in the Mist enters, up to one target creature gets -1/-0 until end of turn.

When Adamant Healer enters, you may move any number of counters from target creature onto another target creature with the same controller.

Flying
Cycling {U} ({U}, Discard this card: Draw a card.)

Cadence (Whenever you cast a spell, if its mana value is greater than this creature's power, put a +1/+1 counter on this creature.)
Hopeless Wanderer can't be blocked.

Whenever a creature enters, each opponent loses 1 life.

Enchant creature
Enchanted creature gets +1/+1.
When enchanted creature dies, you may exile it. If you do, return target creature card from your graveyard to the battlefield.

Flying
Whenever you cast a creature spell, creatures you control get +1/+1 until end of turn.
Whenever you cast a noncreature spell, create a 2/2 red and white Cat Knight creature token.

Put target attacking or blocking creature on the bottom of its owner's library.

{1}{R}: Earnest Labourer gets +2/+0 until end of turn.
{4}{G}: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Enchant creature
When Cage the Dissenter enters, scry 2.
Enchanted creature doesn't untap during its controller's untap step.

Spirited (When this creature enters, you may activate one of its activated abilities without paying its cost.)
{1}, {T}: Look at the top card of your library. You may put the card back or into your graveyard.

Draw two cards, then discard two cards. Then if you cast Price of Wisdom from your graveyard, create a 3/3 blue Sphinx creature token with flying.
Flashback {4}{U}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Hexproof
You may have Glen Hunter assign its combat damage as though it weren't blocked.

Destroy target creature. Mill two cards.

Improve {R/W} ({R/W}: 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.)
Whenever an embattled creature you control attacks, you may exile the top card of your library. During any turn you attacked with an embattled creature, you may play that card. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)