msem-instigator

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

[+2]: Create a 3/3 red Wurm creature token.
[–2]: Up to three target creatures each get +2/+2 until end of turn. Bessie deals 2 damage to each of up to three target creatures.
[–9]: You get an emblem with “Creatures you control have base power and toughness 7/7 and have indestructible.”

Bigroot Valley enters the battlefield tapped.
{T}: Add {R} or {G}.
{1}, {T}: Add one mana of any color.

Trample, haste, indestructible
Whenever a permanent an opponent controls is put into a graveyard from the battlefield, put a +1/+1 counter on target Ooze.

Put a +1/+1 counter on each of up to X target creatures.
Augmented — If you've spent {W}{U}{B}{R}{G} to cast spells this turn, instead put three +1/+1 counters on each of those creatures. They gain trample until end of turn.

Trample, haste
When Blazing Fox enters the battlefield, you may tap an untapped creature you control. If you do, Blazing Fox gets +X/+0 until end of turn, where X is that creature's power.

Gestalt (When this or another creature enters under your control, you may merge it with the one in play, keeping counters and attachments. They become the permanent on top plus all abilities from under it.)
This permanent gets +2/+2 for each card and token merged with it.

Blooming Needles enters the battlefield tapped unless you control another Desert.
{T}: Add {R} or {G}.

Blooming Vista enters the battlefield tapped.
{T}: Add {R} or {G}.
{1}, {T}: Add one mana of any color.

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.”

Vigilance, trample
When Border Guardian enters the battlefield, return a creature you control to its owner's hand.

When Brand New Species enters the battlefield, create a tapped 3/2 green Horror creature token.
Augmented — At the beginning of each end step, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, put a +1/+1 counter on up to one target Horror you control.

Other creatures you control have haste.
Whenever Breach Titan enters the battlefield or attacks, abound. (To abound, you may cast a spell that costs less than this from your hand without paying its mana cost.)
At the beginning of your end step, return another target creature you control to its owner's hand.

You may put a permanent card from your hand onto the battlefield. If it's a planeswalker, it enters the battlefield with five loyalty counters rather than any other amount, and you may activate its loyalty abilities this turn any time you could cast an instant.

Rouse 2. Target permanent gains trample until end of turn if it's a creature. (Distribute two +1/+1 counters among permanents you control. If they aren't creatures, tap them and they become 0/0 creatures in addition to their other types.)

If you would draw a card, you may instead choose creature or land and exile cards from the top of your library until you exile a card of the chosen type. Put that card into your hand and put all other cards exiled this way on the bottom of your library in a random order.

Augmented — Whenever Bril, the Oltenen Emissary enters the battlefield or attacks, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, destroy target permanent.

{T}: Add {C}.
{1}, {T}: Add {R}{G}.

Equipped creature has indestructible as long as it's your turn.
Whenever equipped creature attacks, it gets +X/+0 until end of turn, where X is its power.
Equip {6}

Defender
When Brine Duelist enters the battlefield, create a Treasure token. (It's an artifact with “{T}, Sacrifice this permanent: Add one mana of any color.”)
{W}{U}{B}{R}{G}: Put a +1/+1 counter on Brine Duelist. It loses defender.

Double strike
Whenever you cast a noncreature spell, you may choose one that hasn't been chosen —
• Tap or untap target permanent.
• Draw two cards, then discard a card.
• Creatures you control get +1/+1 until end of turn.

Brutal Struggle deals 2 damage to any target. Put a +1/+1 counter on up to one target creature.

Whenever another creature enters the battlefield, Brutish Champion fights that creature.

Flying
Whenever a permanent you control becomes the target of a spell or ability you don't control, choose one —
• Create a 3/3 red Manticore creature token.
• Create two Treasure tokens.
• Draw a card.

Draw X cards, then abound. (To abound, you may cast a spell that costs less than this from your hand without paying its mana cost.)