msem-instigator

At the beginning of combat on your turn, target creature you control has base power and toughness 5/5 until end of turn.

Creature spells you cast cost {1} less to cast.
Whenever you cast a creature spell, Bellowing Thoctar gets +2/+2 until end of turn.

Choose target creature with the greatest power or tied for the greatest power, then destroy all other creatures.

Aetherize each permanent you control. Exile Beneath the Horizon. (To aetherize a permanent, create a token that's a copy of it, then exile that token.)

Flying
When Benevolent Malach enters the battlefield, create a 1/1 colorless Construct artifact creature token.
Sacrifice Benevolent Malach: Artifacts you control gain indestructible until end of turn.

Whenever Beragnian Brawlmaster or another Warrior enters the battlefield under your control, that Warrior fights target creature an opponent controls.
{R}{W}: Target Warrior creature gets +1/+1 until end of turn.

Prevent all combat damage that would be dealt to and dealt by Bereaved Aristocrat.
Unveil {2}{W}{U} ({2}{W}{U}: Transform this. Unveil only as a sorcery.)

At the beginning of your upkeep, mill a card.
Whenever a creature card is put into your graveyard from anywhere, if that card has flying, you may put a flying counter on Berylscale Alaj. Repeat this process for first strike, double strike, deathtouch, hexproof, lifelink, menace, reach, trample, and vigilance.

You may have Better Half enter the battlefield as a copy of any creature on the battlefield, except it's a Reflection in addition to its other creature types and it has distorted. (It can be blocked by tapped creatures but not untapped creatures.)

Exile target nonland permanent. Its controller gains 5 life.

Creatures you control get +1/+1 until end of turn.
Artifact creatures and Elementals you control get +1/+1 until end of turn.

When Beyond the Boneyard enters the battlefield, exile another target nonland permanent until Beyond the Boneyard leaves the battlefield.
Your opponents can't cast spells that share a card type with the exiled card during postcombat main phases.

Menagerie — This spell costs {2} less to cast if there are five or more creature types among creatures you control.
Destroy target creature with power or toughness 4 or greater.

(Add a quest counter as this enters. Sacrifice after 4.)
Whenever a creature enters the battlefield under your control, add a quest counter.
1, 2 — Exile target nonland permanent an opponent controls until target creature you control leaves the battlefield.
3 — Each player may scry 1.
4 — Put all cards exiled with Bind the Great Evil into their owners' graveyards.

When Bind the Mind enters the battlefield, each poisoned opponent reveals their hand. Then choose a nonland card name.
Spells with the chosen name can't be cast.

Enchant creature
Enchanted creature can't attack or block alone.

Flash
When Binding Stones enters the battlefield, exile target creature with power 3 or less until Binding Stones leaves the battlefield.

Return up to one target spell to its owner's hand.
Create two 1/1 blue Elemental creature tokens with flying. They can't block this turn.

Lifelink
At the beginning of your end step, if you've gained 3 or more life this turn, create a 2/2 white Bird creature token with flying.

Create a 1/1 blue Bird creature token with flying. (Cast a copy of this spell once while this creature is on the battlefield.)

Legacy (You may play this side of this card only from your graveyard. Exile it if it would leave the battlefield or not resolve.)
Permanents you control have lifelink and “{T}: Add one mana of any color.”

You gain 2 life. Then if you have more life than an opponent, draw a card.
At the beginning of your upkeep, if Bittersweet Reunion is in your graveyard, you may pay {1}{W} and exile it. If you do, you may copy it and cast the copy without paying its mana cost.

When Bizarre Dreams enters the battlefield, destroy up to one target artifact or enchantment.
{3}{W}, Sacrifice Bizarre Dreams: Create two 1/1 blue Elemental creature tokens with flying. They can't block this turn.

When Bjarndyr Mender enters the battlefield, other creatures you control get +1/+1 and gain indestructible until end of turn.

When Bjarndyr Militant enters the battlefield, return target Aura card or card with fabled from your graveyard to your hand.