msem-instigator

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.”)

Exile target artifact or enchantment.

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

Improve {1} ({1}: 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.)
When Bridgehaven's Finest enters, create a 1/1 colorless Human creature token.
Other creatures you control get +1/+1 as long as Bridgehaven's Finest has two or more counters on it.

Prowess
Unveil {2}{U}{R} ({2}{U}{R}: Transform this. Unveil only as a sorcery.)

Spells cost {1} more to cast for each colored mana symbol in their mana cost beyond the first. (For example, a spell with mana cost {W}{W} would cost {1}{W}{W} to cast.)

Flying, haste
At the beginning of the end step, sacrifice Brightflame Phoenix.
Retrace (You may cast this card from your graveyard by discarding a land card in addition to paying its other costs.)

Choose one —
• Brimstone Cleansing deals 4 damage to target tapped creature.
• Exile target enchantment.

Whenever Brine Kelpie attacks, you may tap target creature an opponent controls.
Ride {2}{U} ({2}{U}: Transform this and attach it to target creature you control without a Steed. Ride only as a sorcery.)

Target creature gets +3/+0 until end of turn. Mill three cards.

Choose one —
• Destroy target artifact or enchantment.
• Return target creature to its owner's hand.
• Draw a card.

When Broadside Raider enters, create a 1/1 blue and red Pirate creature token with haste.

Flash
Whenever you cast your second spell each turn, put a +1/+1 counter on Brooding Replacement.

Two target creatures you control each get +2/+1 until end of turn.

(Add a quest counter as this enters. Sacrifice after 3.)
1, 2 — Whenever you attack with exactly two creatures, add a quest counter.
3 — Reveal the top four cards of your library. You may put a creature card from among them into your hand. Put the rest on the bottom in a random order.
Put two +1/+1 counters on each of up to two target creatures you control.

Brushfire deals 3 damage to target creature. If that creature would die this turn, exile it instead.

Target opponent sacrifices a creature.
Rerun (If you cast this from your hand, exile it as it resolves. Whenever a creature you control dies, you may cast this card from exile without paying its mana cost.)

When Bubbledome Chorister enters, create a green Aura enchantment token named Sanctum's Gift attached to target creature. The token has enchant creature and “Enchanted creature has ‘{T}: Add {G} for each enchanted creature you control.'”

When Bubblespout Sentry enters, look at the top card of your library. You may put it into your graveyard.

Experience (Whenever this creature attacks, if it has fewer than three +1/+1 counters on it, put a +1/+1 counter on it.)
When Budding Companion has three or more +1/+1 counters on it, remove them all and transform it.

Whenever you cast a spell for its showcase cost, create a 2/2 blue Drake creature token with flying.

{3}{U}, {T}: Copy target instant or sorcery spell you control. You may choose new targets for the copy.

Target player mills four cards, then mills an additional four cards for each Curse attached to them.

Double strike, trample
Arise {3}{R}{W} ({3}{R}{W}, Exile this from your graveyard as a sorcery: Create a black token copy of it that's also a Zombie and can't block.)
When Bugrund arises, you may put an Equipment card from your hand or graveyard onto the battlefield attached to it.

Flash
Enchant creature
Enchanted creature gets +1/+1 and has hexproof.