msem-instigator

At the beginning of your end step, put an encroachment counter on Approach of Old Lovi, then it deals X damage to any target and you gain X life, where X is the number of encroachment counters on Approach of Old Lovi.

Arid Causeway enters tapped unless you control another Desert.
{T}: Add {R} or {W}.

Arsenal Curator gets +1/+1 as long as you control a Plains.
{2}{W}: Untap target creature you control. It gets +0/+1 until end of turn.

Flying
Whenever August Sunbird attacks, create a token that's a copy of another target creature you control, except it's 1/1, and it's tapped and attacking. Sacrifice the token at the beginning of the next end step.

Avaz Sanctuary enters tapped.
Satrapies you control have “{T}: Add {R} or {W}.”

[+1]: Tap up to one target creature. Azun, Sheriff of Daisite deals 1 damage to each opponent.
[–1]: Exile another target nonland permanent until Azun, Sheriff of Daisite leaves the battlefield.
[–7]: Detain each permanent target opponent controls. (Until your next turn, those permanents can't attack or block and their activated abilities can't be activated.)

{T}, Pay 1 life: Add {R} or {W}.
{1}, {T}, Sacrifice Backstage Rooms: Investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

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

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

When Batrest's Forgemaster enters, 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.

Batrest, Fellor Leader gets +1/+1 for each Equipment attached to it.
When Batrest enters, create Astrina, Forged for Glory, a legendary colorless Equipment artifact token with “Equipped creature gets +4/+4 and has first strike and lifelink” and equip {4}. Attach it to Batrest.

Battalion — Whenever Battleborn Brute and at least two other creatures attack, Battleborn Brute gets +2/+2 until end of turn. Untap it.

When Battlefield Tiger enters, create two 1/1 white Soldier creature tokens.

Beachhead Partisan has first strike as long as it's attacking.
When Beachhead Partisan enters, it deals X damage to any target, where X is the number of tapped creatures you control.

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

{1}{R/W}: Untap Blade of the Long Night.

Up to two target creatures you control each get +2/+0 and gain first strike and haste until end of turn.
Orchestrate—Tap an untapped red and white creature you control or an untapped red creature you control and untapped white creature you control. (You may exile this card from your hand anytime you could cast a sorcery for its orchestrate cost. When you next resolve a spell, you may cast this from exile without paying its mana cost.)

Target creature gets +2/+2 until end of turn.
Fuse (You may cast one or both halves of this card from your hand.)

Other Hounds you control get +1/+1.

Double strike
{1}{R}{W}: Target creature gains double strike until end of turn. Activate only if Bravery is in your graveyard.

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

Double strike, vigilance
At the beginning of combat on your turn, create X 1/1 red Dwarf creature tokens with haste, where X is the number of embattled nontoken creatures you control. (A creature is embattled if it has a counter on it or a permanent you control attached to it.)

Permanents you control with mana value 1 or less have first strike, haste, and lifelink.

When Callous Renegade enters, you may return target Rebel creature card with mana value 4 or less from your graveyard to the battlefield. It gains haste until end of turn.

Battalion — Whenever Callous Trainer and at least two other creatures attack, create a 1/1 white Warrior creature token that's tapped and attacking.