msem-instigator

When Rat King enters, create two 1/1 black Rat creature tokens with “This creature can't block.”
Whenever Rat King or another creature you control dies, each opponent loses 1 life and you gain 1 life.

Flying
When Razorwing Champion enters, creatures you control get +1/+1 and gain vigilance until end of turn.

Put target artifact, enchantment, or card in a graveyard on the bottom of its owner's library.

Choose two target creatures controlled by different players. Return those creatures to their owners' hands.

Menace
Regal Dragoon gets +1/+1 as long as you control a legendary creature.

Flash
When Reinforced Platemail enters, you may attach it to target creature you control.
Equipped creature you control gets +1/+2.
Equip {3}

Renegade Spellweaver can't be blocked as long as you've foretold a card or cast a foretold spell this turn.

At the beginning of each end step, you may exile target creature card with mana value X or less from your graveyard, where X is the amount of life you gained this turn. If you do, create a token that's a copy of it.

Foretell {3}{G} (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.)
This spell's foretell cost costs {3} less to pay if an opponent drew two or more cards this turn.
Create a 5/5 green Beast creature token with trample.

Flying
Rezzal, the Loamfeaster gets +1/+1 for each nonland card exiled with it.
You may play lands exiled with Rezzal.
{1}{B/G}: Exile target card from an opponent's graveyard. Activate only outside of combat.

Hexproof from mana value 3 or less
{W}: Rhysta of the Roses gains lifelink until end of turn.
{B}: Rhysta of the Roses gains menace until end of turn.

Put a +1/+1 counter on up to one target creature.
Draw a card.

Foretell {2}{R} (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.)
Attacking creatures get +2/+0 until end of turn. If this spell was foretold, those creatures also gain trample until end of turn.

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

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.

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.