msem-instigator

Exile target nonland card with mana value 2 or less from your graveyard. Copy it. You may cast the copy without paying its mana cost.
Exile Breach the Lilies.

Counter target spell unless its controller discards two cards.

Destroy target artifact or tapped creature.

You may put a permanent card from your hand onto the battlefield. If it's a planeswalker, it enters with five loyalty counters rather than any other amount, and you may activate its loyalty abilities this turn any time you could cast an instant.

Put a number of +1/+1 counters on target creature you control equal to that creature's power.
Spell mastery — If there are two or more instant or sorcery cards in your graveyard, you may have that creature fight another target creature. (Each deals damage equal to its power to the other.)

Rouse 2. Target permanent gains trample until end of turn if it's a creature. (Distribute two +1/+1 counters among permanents you control. If they aren't creatures, tap them and they become 0/0 creatures in addition to their other types.)

Enchant creature
Enchanted creature gets +2/+2 as long as it's an Actor. Otherwise, it gets -2/-2.

Double your life total. (Then exile this card. You may cast the creature later from exile.)

Trample
Whenever Breaker of Cities deals combat damage to a player, create a 1/1 white Soldier creature token with vigilance.
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.)

When Breaker of Secrets enters, each player mills three cards from each of their libraries.
Recite {U} (You may cast this creature from your graveyard for its recite cost. If you do, exile it when it enters or if it would leave the battlefield.)

Until end of turn, target creature gets +2/+2 and gains trample and “Whenever this creature deals combat damage to a player, investigate.” (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

Whenever Breakneck Barque becomes blocked by a creature, Breakneck Barque deals 3 damage to that creature.
Crew 3 (Tap any number of creatures you control with total power 3 or greater: This Vehicle becomes an artifact creature until end of turn.)

Exile target artifact or enchantment.

Breath of Hao'Tai deals 4 damage to any target.

{1}{G}: Target land you control becomes a 3/3 green Elemental creature until end of turn.
{1}{U}: Target enchantment you control becomes a 2/2 blue Nymph creature with flying until end of turn.

Exile target creature. You gain 2 life.

{T}: Add {C}.
{1}, {T}: Add one mana of any color. When that mana is spent to cast an Adventure spell, scry 1.

Flying

Breezerider has flying as long as you control a Nymph.
Breezerider has hexproof as long as you control another Monkey.

Flying, trample
Whenever Bretala of Redsky attacks, it gains double strike until end of turn unless defending player sacrifices a creature.

Choose a creature type. Return up to two target creature cards of the chosen type from your graveyard to your hand.

{T}: Add one mana of any color. Spend this mana only to cast an instant or sorcery spell.

If you would draw a card, you may instead choose creature or land and exile cards from the top of your library until you exile a card of the chosen kind. Put that card into your hand and put all other cards exiled this way on the bottom of your library in a random order.

When Briarform Apothecary enters, create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)
Sacrifice a token: Briarform Apothecary gets +2/+2 until end of turn.

Hexproof
Whenever attackers are declared, the active player may pay {2} for each creature attacking you. Then you may have Bridge Kalak become an X/X Troll creature until end of turn, where X is the number of times that player didn't pay mana this way.