msem-instigator

Haste
Rapport — Whenever Maghbri Hunter and at least one other creature you control become tapped, Maghbri Hunter gets +2/+1 until end of turn.

Equipment spells you cast cost {1} less to cast.
Equip abilities you activate cost {1} less.

Engage (This creature must be blocked each combat if able.)
{R}: Mettlesome Watchkeeper gets +1/+0 until end of turn.

Dragon spells you cast cost {1} less to cast.
{1}{R}: Until end of turn, Miyoga Dragonsoul becomes a 2/2 red Dragon creature with flying and “{R}: Miyoga Dragonsoul gets +1/+0 until end of turn.” Activate only as a sorcery.

Stampede — Whenever Nacatl Skirmisher and a creature with greater power attack, creatures you control get +1/+0 until end of turn.
{R}, Sacrifice Nacatl Skirmisher: Destroy target artifact.

Whenever you cast a spell, Nightfire Adept gets +3/+0 until end of turn if that spell has the same name as a card in your graveyard.

Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)
Whenever you cast an enchantment, instant, or sorcery spell, Noble Barracuda gets +1/+0 until end of turn. Scry 1.

Whenever you attack with one or more Pirates, create that many 1/1 white Bird creature tokens with flying that are tapped and attacking. At end of combat, choose one of those tokens, then exile the rest.

Whenever Professor's Assistant becomes tapped, add {R}. Until end of turn, you don't lose this mana as steps and phases end.

{R}, {T}, Exert Provoker of Mountains: Create an X/X red Elemental creature token, where X is the number of spells you've cast this turn. (An exerted creature won't untap during your next untap step.)
{X}{X}{R}, {T}, Sacrifice Provoker of Mountains: Provoker of Mountains deals X damage to any target.

When Royal Retriever enters or when a creature you control scavenges it, you may discard a card. If you do, draw a card.
Scavenge {R} ({R}, Exile this card from your graveyard: Put a number of +1/+1 counters equal to this card's power on target creature. Scavenge only as a sorcery.)

{2}{R}: Ruthless Mastiff gets +3/+0 until end of turn.

Whenever one or more creatures you control deal combat damage to a player, you may discard a card. If you do, draw a card.
{2}{R}, {T}, Exile two cards from your graveyard: Sarrutu Flamebinder deals 2 damage to any target.

Prowess
Each instant and sorcery card with mana value 3 or less in your hand has inscribe. The inscribe cost is equal to its mana cost increased by {1}{U/R}. (Pay that card's mana cost increased by {1}{U/R}: Exile that card from your hand inscribed on a creature you control. Whenever that creature attacks, its controller may cast a copy of the inscribed card without paying its mana cost. Inscribe only as a sorcery.)

Colossal 3—{4}{R} (You may cast this for its colossal cost to have it enter with three +1/+1 counters; or pay {4}{R} as a sorcery: Put three +1/+1 counters on it if it has none.)
When Storm-Eye Salamander's colossal ability puts one or more counters on it, exile the top three cards of your library. Until the end of your next turn, you may play one of those cards.

Menace, prowess

Temple Recluse gets +1/+0 as long as you've cast a noncreature spell this turn.

Ferocious — When Volcanic Whelp enters, if you control a creature with power 4 or greater, Volcanic Whelp gets +3/+0 and gains haste until end of turn.

Prowess
{1}{R}: Until end of turn, if an instant, sorcery, or Dragon source you control would deal damage to a permanent or player, it deals that much damage plus 1 to that permanent or player instead. Activate only once each turn.

Whenever Wandering Conqueror attacks, it explores. (Reveal the top card of your library. Put it into your hand if it's a land. Otherwise, put a +1/+1 counter on this creature, then you may put that card in your graveyard.)
As Wandering Conqueror explores a land, you may put that card into your graveyard. Whenever you do, Wandering Conqueror deals 2 damage to target player or planeswalker.

Whenever you cast a spell, Wandering Precursor gets +1/+0 until end of turn for each color of mana spent to cast that spell.

Double strike, haste

When Alder Courtier dies, you gain 4 life.

Trample
{T}, Sacrifice another creature: You gain 3 life.
Whenever another creature you control dies, put a +1/+1 counter on Bloodbriar Archdruid.

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.)