msem-instigator

Spells you cast that target Risti Operative cost {1} less to cast.
Abilities you activate that target Risti Operative cost {1} less to activate.

Reach
When Risti Watchkeeper enters, rediscover a creature card. (Look at the top card of your library. You may reveal it and put it into your hand if it's a creature card. Otherwise, put it back or into your graveyard.)

Target creature gets -4/-4 until end of turn. When it dies this turn, create two 1/1 black Worm creature tokens.

At the beginning of your upkeep, you lose 1 life, then investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)
Whenever you sacrifice a permanent, each opponent loses 1 life.

At the beginning of your upkeep, if an opponent has more life than you, create a 4/4 red Elemental creature token with haste and “Creatures blocking this creature have winnow.” (Damage dealt to a creature with winnow causes its controller to lose that much life.)

Bloodprice {B} (You may cast this card by sacrificing a creature and paying its bloodprice.)
Destroy target creature.

When Ritesinger Shaman dies, each player discards a card.

As Ritual Preparations enters, choose a color.
You don't lose unspent mana of the chosen color as steps and phases end.

Bloodprice {2}{B} (You may cast this card by sacrificing a creature and paying its bloodprice.)
Create X 2/2 black Demon creature tokens, where X is one plus the number of creatures that died this turn.

Destroy all creatures with mana value 3 or less.

Menace
Sabotage — Whenever an opponent or permanent an opponent controls becomes the target of a spell you control, each opponent discards a card.

Choose one or both —
• Riverboat Assault deals 3 damage to target creature.
• Target creature gets +3/+3 until end of turn.

{U}, {T}: You may tap or untap another target creature.
Whenever one or more other creatures you control deal combat damage to a player, you may untap Riverchase Diver.

Harmony — Untap target permanent.
Whenever you cast an instant or sorcery spell, harmonize. (Trigger up to one harmony of one permanent you control.)

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

Flying
Whenever Rivha and at least two other creatures attack, exile all other attacking creatures you control. For each creature exiled this way, create a 3/3 white Angel creature token with flying that's tapped and attacking.

When Rixia, Rift Shunted enters, target creature can't be blocked this turn.
Whenever a creature you control deals combat damage to an opponent, you may aetherize it. (To aetherize, create a token that's a copy of it, then exile that token.)

As Road to Alratha enters, choose near or far.
Whenever you attack,
• Near — Creatures you control get +1/+1 until end of turn.
• Far — Put a +1/+1 counter on target creature you control. Untap it.

Search your library for up to three basic land cards, reveal those cards, shuffle, then put one of them into the battlefield tapped, one into your hand and one on top of your library.

First strike
Whenever a creature dealt damage by Roadside Reaper this turn dies, you may discard a card. If you do, put a +1/+1 counter on Roadside Reaper and draw a card.

You may play this card transformed.
Trample

Flying
Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)

Creatures you control get +2/+0 and gain menace until end of turn. (They can't be blocked except by two or more creatures.)

{1}{R}: Roaring Dracowyrm gets +2/+0 until end of turn. Activate only once each turn.

Whenever Roaring Illusion attacks alone, for each other creature you control, create a token that's a copy of that creature and that's tapped and attacking. Exile those tokens at the beginning of the next end step.