msem-instigator

Elemental, instant, and sorcery spells you cast cost {1} less to cast.

Flying
When this creature enters, return target creature card with flying from your graveyard to your hand.

(Transform this if it's not attached to a creature. Pay {B} as a sorcery to unattach it.)
Enchant creature you control
Herald of Death's rider gets +1/+1.
Sacrifice a creature: Herald of Death's rider gets +2/+2 until end of turn.

Beckon Ox {1}{W} ({1}{W}: This enchantment permanently becomes an Ox creature in addition to its other types.)
Vigilance
Whenever a creature or another enchantment you control enters, you gain 1 life.

(Transform this if it's not attached to a creature. Pay {4}{G} as a sorcery to unattach it.)
Enchant creature you control
Herdstrider's rider gets +1/+1 for each land you control and has trample.
Whenever Herdstrider's rider attacks, create an X/X green Elephant creature token with trample that's tapped and attacking, where X is that creature's power. Exile that token at the end of combat.

When this creature enters, look at target opponent's hand. You may exile a nonland card from it. For as long as that card remains exiled, its owner may play it. A spell cast this way costs {2} more to cast.
Arise {2}{W}{W} ({2}{W}{W}, Exile this from your graveyard as a sorcery: Create a black token copy of it that's also a Zombie and can't block.)

This spell can't be countered.
Enchant land
At the beginning of combat on your turn, untap enchanted land. It becomes a 6/6 green Lizard creature with haste until end of turn. It's still a land.

Assault {B} (Whenever this attacks, if it has no +1/+1 counters on it, you may pay its assault cost to put a +1/+1 counter on it.)
When Hilaback Outriders assaults, it gains menace until end of turn.

Civilized — As long as you control an artifact, a creature, and an enchantment, prevent all combat damage that would be dealt to Hirsute Champion.

Reprise {2}{W} (As you cast an instant or sorcery spell, you may exile one card with reprise from your graveyard and pay its reprise cost. If you do, add its effects to that spell.)
You gain 2 life. Then distribute X +1/+1 counters among creatures you control, where X is the amount of life this spell caused you to gain.

When Hitana's Implements enters, draw a card.
{1}, {T}: Add one mana of any color.
Augmented — At the beginning of each end step, if you've spent {W}{U}{B}{R}{G} on spells this turn, exile Hitana's Implements. If you do, create a 5/5 blue Horror creature token.

Whenever another Knight or Soldier you control enters, target player loses 1 life.

Other Pirates you control get +1/+0.
Whenever another Pirate you control enters, Hookhand Freebooter deals 1 damage to any target.
When Hookhand Freebooter dies, create a Bullet token. (It's an artifact with “{T}, Sacrifice this artifact: It deals 1 damage to any target.)

As Horizon of Origins enters, you may reveal an Island or Mountain card from your hand. If you don't, Horizon of Origins enters tapped.
{T}: Add {U} or {R}.

Trample
Harmony — Put a +1/+1 counter on target Warrior you control. You gain 1 life.
Whenever one or more Warriors you control deal combat damage to a player, harmonize. (Trigger up to one harmony of a permanent you control.)

Haste
When Horse Thief enters, you may gain control of target creature or Steed until end of turn. It gains haste until end of turn. If it's a Steed, attach it to Horse Thief.

Whenever this creature enters or attacks, create a 2/1 white Soldier creature token. Exile up to one target nonland permanent with mana value 3 or less an opponent controls until that token leaves the battlefield.
Other permanents you control have ward {1}.

Whenever this creature enters or attacks, each player discards a card. If one or more land cards were discarded this way, this creature gains deathtouch until end of turn.
At the beginning of each opponent's end step, if that player didn't cast a spell this turn, that player loses 2 life and you gain 2 life.

Whenever this creature enters or attacks, put two -1/-1 counters on up to one target creature with power less than this creature's power.
Whenever another creature dies, you gain 2 life. If you controlled that creature, draw a card.

Whenever this creature enters or attacks, you may put a creature card with mana value 2 or less from your hand onto the battlefield. If you do, draw a card. Sacrifice that creature at the beginning of the next end step.
If a creature would enter under your control during combat on your turn, that creature enters tapped and attacking.

Return target creature card from your graveyard to the battlefield if its mana value is 3 or less or if this spell was foretold.
Foretell {3}{W} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Whenever an opponent casts a spell, if no mana was spent to cast it or it has mana value greater than the number of lands that player controls, counter that spell.
{G/W}, Sacrifice this creature: Citizens and Peasants you control get +1/+1 and gain indestructible until end of turn.

When this creature enters, create a 2/2 black Zombie creature token. That token seeks secrets and gains haste until end of turn. (Give it that Oath Aura. Fulfill it by attacking with it and two or more other creatures to draw a card.)

{T}: Add {C}.
Ascend—Tap ten untapped permanents you control. (Tap ten untapped permanents you control: Exile this land, then return it to the battlefield transformed. Ascend only as a sorcery.)

When Humble Shepherd enters, create a 0/1 white Sheep creature token.
{T}, Tap an untapped Sheep you control: Add one mana of any color.