msem-instigator

If you would catalyze, catalyze twice instead. (The next spell you cast this turn costs {1} less to cast.)
You may pay an additional {2} as you cast a spell. If you do, reveal the bottom card of your library. You may put it into your graveyard or on top of your library.

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)

When Benthic Alchemist enters, draw a card, then discard a card, then mill a card.
Whenever you cast an instant or sorcery spell, create a 1/1 colorless Elemental creature token. It gains haste until end of turn.

When Benthic Tidebreaker enters, reveal the top card of each player's library and exile one of those cards. You may play that card for as long as it remains exiled, and you may spend blue mana as though it were mana of any color to cast it.
Evoke {1}{U} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Armed — Whenever Beragnian Intimidator attacks, if it's equipped, target creature can't block this turn.

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.

Bjarndyr Bruiser gets +2/+2 as long as it's embattled. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)

Trample
Revive {5}{B} ({5}{B}, Exile this card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)

This spell costs {1} less to cast for each card in your graveyard.
Arise {9}{B}. This ability costs {1} less to activate for each other card in your graveyard. ({9}{B}, Exile this from your graveyard as a sorcery: Create a black token copy of it that's also a Zombie and can't block.)

Blighted Unicorn can't block.
Ride {3}{B} ({3}{B}: Transform this and attach it to target creature you control without a Steed. Ride only as a sorcery.)

When this creature enters, put two -1/-1 counters on a creature you control.
{B}: Target creature with a counter on it gains deathtouch until end of turn.

{4}{R}: Blind Tunneler gets +3/+0 until end of turn.

Whenever Blood Constrictor becomes blocked by a creature, you gain life equal to that creature's toughness.

This spell costs {1} less to cast for each creature with one or more counters on it.
Flying, vigilance

Sacrifice another creature: Put a +1/+1 counter on target creature you control. Activate only as a sorcery.

Bloodline Zealot gets +2/+0 and has menace as long as you've sacrificed a permanent this turn.

When Bloodpact Collector enters, destroy target creature an opponent controls that was dealt damage this turn or has a -1/-1 counter on it.

Discard a card: Bloodshot Berserker gets +1/-1 until end of turn. Any player may activate this ability.

Trample
Bloodthirsty Berserkers can't be blocked by more than one creature.

Flying
{1}, Sacrifice a creature: Put a +1/+1 counter on Bloodthirsty Manticore. It gains indestructible until end of turn. Tap it.
Surpass {4}{B}{R} ({4}{B}{R}: Transform this creature. This costs {1} less to activate for each counter on it. Activate only as a sorcery.)

At the beginning of your first main phase, add an amount of {G} equal to Bloomhorn's power.

Whenever Boghex Witch deals combat damage to a cursed player, that player loses the game.
{2}{B}: Look at the top five cards of your library. You may reveal a Curse card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)

Haste
Augmented — Whenever you cast a spell, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, put a +1/+1 counter on Bolstered Guardian. It loses this ability and gains “Whenever this attacks, it deals 2 damage to each of up to two targets.”