msem-instigator

When Baneblade Stalker enters the battlefield, proliferate. (Choose any number of permanents and/or players with counters on them, then give each another counter of each kind already there.)

When Banished Prophet enters the battlefield, you may remove a counter from a permanent you control. If you do, put a +1/+1 counter on another target creature you control.

When Banishing Initiate enters the battlefield, you may exile target nonland permanent you don't control until Banishing Initiate leaves the battlefield.
At the beginning of your end step, sacrifice Banishing Initiate if a card exiled with it has mana value 3 or greater.

Trample
When Bank Skimmer enters the battlefield, create a green Aura enchantment token named Turtle's Valor attached to target creature. The token has enchant creature and “Enchanted creature gets +X/+X, where X is its mana value.”

When Barbarian Hoarders enters the battlefield, you may attach target Equipment you control to it.

When Barbarian Intimidator enters the battlefield, target creature can't block this turn.
When Barbarian Intimidator enters the battlefield, prevent all combat damage that would be dealt to target creature this turn.

When Barhopping in Minei enters the battlefield, draw up to four cards, then put twice that many drink counters on Barhopping in Minei.
Your maximum hand size is reduced by the number of drink counters on Barhopping in Minei.

When Barricade Patrol enters the battlefield, create a 1/1 white Human Soldier creature token.
Whenever another creature you control dies, Barricade Patrol deals 1 damage to target player.

When Basalt Ritualist enters the battlefield, you may sacrifice a land or exile a land card from your graveyard. When you do, exile target creature, instant, or sorcery card from your graveyard. Until the end of your next turn, you may play that card. If that spell would be put into a graveyard, exile it instead.

Menace
Cat creatures you control have menace.
When Basat Priest enters the battlefield, create a 2/2 white Cat creature token.

When Batiga Escort enters the battlefield, create a 1/1 blue Bird creature token with flying.
{2}{W}, {T}: Put a +1/+1 counter on each creature you control with flying.

When Batrest's Forgemaster enters the battlefield, you may search your library for an Equipment card, reveal it, put it into your hand, then shuffle.
Whenever Batrest's Forgemaster attacks, Equipment spells you cast this turn cost {2} less to cast.

When Battlemage's Disruption enters the battlefield, you may return target creature to its owner's hand.
{3}{U}, Sacrifice Battlemage's Disruption: Return target creature to its owner's hand.

When Bauble Collector enters the battlefield, you may return another permanent you control to its owner's hand.

When Bayou Courier enters the battlefield, you may pay 2 life. If you do, create a 3/2 green Crocodile creature token with trample.

Concord — When Bazaar Equestrian enters the battlefield, if there are four or more card types among permanents you control, you gain 4 life.

When Bearer of Old Growth enters the battlefield, choose one —
• Untap up to two target artifacts.
• Draw a card.

When Bearer of Silk Chains enters the battlefield, gain control of target nonland permanent until Bearer of Silk Chains leaves the battlefield. If that permanent is a Horror, gain control of it instead.

When Bearer of Tormented Truths enters the battlefield, look at target player's hand. You may exile a nonland card from among them. If you do, that player draws a card.
You may play cards exiled with Bearer of Tormented Truths, and you may spend mana as though it was mana of any color to cast them.

When Bearer of the Lantern enters the battlefield, you gain 3 life.
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

Concord — When Beetleback Forager enters the battlefield, if there are four or more card types among permanents you control, return target card from your graveyard to your hand.

When Beguiling Witch enters the battlefield, nourish 1. (To nourish 1, either put a +1/+1 counter on this creature or create a 1/1 white Citizen creature token.)
Whenever another creature dies, each opponent mills X cards, where X is Beguiling Witch's power.

Augmented — When Behavioral Specialist enters the battlefield, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, create a 1/1 blue Elemental creature token with flying.
Whenever one or more creatures you control deal combat damage to an opponent, you may draw a card. If you do, discard a card.

When Bellani Mystic enters the battlefield, target player mills two cards.

Enchant creature you control
Enchanted creature gets +3/+3.
When Belligerence enters the battlefield, enchanted creature fights target creature an opponent controls.
When enchanted creature dies, if it's a Warrior, return Belligerence to its owner's hand.