msem-instigator

This spell costs {1} less to cast for each creature that attacked this turn.

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

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

Look at the top four cards of your library. You may reveal a permanent card from among them and put it into your hand. Put the rest on the bottom of your library in any order.

Destroy target artifact or enchantment. If that permanent was a token, proliferate. (Choose any number of permanents and/or players with counters on them, then give each another counter of each kind already there.)

Target creature you control gets +2/+2 and gains hexproof until end of turn.

When Border Seeker dies, search your library for a basic land card, put it onto the battlefield tapped, then shuffle. Then you gain 1 life for each land you control.

{G}, {T}, Remove a +1/+1 counter from a creature you control: Create a 2/2 green Ox creature token.

Bound by Nature enters with X nature counters on it.
You can't cast nonpermanent spells.
Creatures you control get +1/+1 for each nature counter on Bound by Nature and have “{T}: Add {G}.”

For each creature token you control, create a token that's a copy of that creature.

Untap target creature you control. It gets +4/+4 and gains reach until end of turn.

Trample
{1}{G}: Brackish Kelpie gets +2/+2 until end of turn. Activate only once each turn.

Enchant creature
When Bramble Armor enters, put a +1/+1 counter on enchanted creature.
{G}, Sacrifice Bramble Armor: Enchanted creature gains indestructible end of turn. Tap it.

Branch Prowler can't be blocked except by creatures with flying.

Erratic (When this creature dies, reveal the top four cards of your library. Put a creature card that costs less than this revealed this way onto the battlefield and the rest on the bottom of your library in any order.)

You may play an additional land this turn. Scry 1.

When Brawlhost Escapee dies, create a Function token with “Target creature you control fights target creature you don't control.” (It's an enchantment. As you cast an instant or sorcery spell, sacrifice any number of Functions to add their effects to that spell.)

Enchant creature you control
When Brawnsurge enters, enchanted creature deals damage equal to its power to up to one target creature an opponent controls.
Enchanted creature gets +1/+1 and has trample.

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.

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.)

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.

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.

This spell costs {2} less to cast if you control a transformed permanent.
Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.