msem-instigator

{7}{U}: Tap up to three target nonland permanents. This ability costs {2} less to activate if you control a legendary creature.

Flying
When Rooftop Robber enters, another target Pirate or Rogue you control gets +2/+0 and can't be blocked this turn.

Rosesworn Knight gets +1/+1 as long as it's embattled. (A creature is embattled if it has a counter on it or a permanent you control attached to it.)

The first creature spell you cast each turn costs {2} less to cast.
At the beginning of your upkeep, return a creature you control to its owner's hand. If you do, you draw cards and gain life equal to its power.

Trample
When Rundfora Communionist enters, return a creature you control to its owner's hand.
Creature spells you cast cost {1} less to cast.

Flying
When Rushwater Hunter enters, you may return target creature to its owner's hand.

Improve {1}{U} ({1}{U}: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)
At the beginning of your end step, if one or more embattled creatures you controlled dealt damage to a player, you may draw a card. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)

Haste
Whenever an embattled creature you control deals combat damage to a player, you may pay {2}{G}. If you do, create a token that's a copy of that creature, except the token isn't legendary if the creature is legendary. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)

When Ryleth, Vengeful Shadow enters, create two 1/1 green Elf creature tokens.
Whenever you attack, you may pay {1}{B/G}. When you do, return target creature card with mana value less than or equal to the number of attacking creature tokens you control from your graveyard to the battlefield tapped and attacking.

Sacred Summits enters tapped.
{T}: Add one mana of any color among the color identity of legendary creatures and planeswalkers you control or legendary cards in your command zone.

Flying, prowess
Once each turn, when you cast a noncreature spell, you may create a 4/4 blue Sphinx Wizard creature token with flying, then scry 1.
{2}{U}{U}, Discard Sage of the Hereafter: Create a 4/4 blue Sphinx Wizard creature token with flying, then scry 1. Activate only as a sorcery.

Whenever an opponent attacks you and/or one or more planeswalkers you control, you may draw a card.

Trample
{2}{R}: Santriza Arsonist gets +3/+0 until end of turn.

Menace
When Santriza Gang-Boss enters, it deals X damage to any target, where X is the number of Pirates and/or Rogues you control.

Flying
Improve—{1}{B/R}, Sacrifice a creature. ({1}{B/R}, Sacrifice a creature: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)
Whenever another creature you control dies, each opponent loses 1 life and you gain 1 life. If that creature was sacrificed, instead each opponent loses 2 life and you gain 2 life.

Trample
Savage Mammoth gets +1/+1 for each land you control.
Ride {4}{G} ({4}{G}: Transform this and attach it to target creature you control without a Steed. Ride only as a sorcery.)

(Transform this if it's not attached to a creature. Pay {1}{R} as a sorcery to unattach it.)
Enchant creature you control
Scale Bearer's rider gets +4/+3 and has flying and haste.
Whenever Scale Bearer's rider attacks, you may pay {2}{R}. If you do, it deals damage equal to its power to target creature or planeswalker.

Whenever Scarhide, Arsenal Crafter attacks, create a token that's a copy of an Equipment attached to Scarhide and attach the token to Scarhide. When you can't, arm it. (Create a colorless Equipment artifact token with “Equipped creature gets +1/+0” and equip {2}, then attach it to that creature.)

Whenever Scavenger of the Old Bay deals combat damage to a player, draw a card.
Ride {1}{U} ({1}{U}: Transform this and attach it to target creature you control without a Steed. Ride only as a sorcery.)

Scion of Belmord has lifelink as long as it's embattled. (A creature is embattled if it has a counter on it or a permanent you control attached to it.)

When Scion of Sarrithaz enters, create a 2/2 black Zombie creature token.
{2}{B}, Sacrifice a creature: Draw a card.

Vigilance
Other Knights and Soldiers you control get +1/+1.
{2}{B}, {T}, Sacrifice a Knight or Soldier: Destroy target creature or planeswalker. Activate only as a sorcery.

Flying, haste
Ride {1}{R} ({1}{R}: Transform this and attach it to target creature you control without a Mount. Ride only as a sorcery.)

({T}: Add {U}.)
As Seaside Grotto enters, you may pay 1 life. If you don't, Seaside Grotto enters tapped.
Basic lands you control have “{T}: Add {U}.”