msem-instigator

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

As an additional cost to cast this spell, put two -1/-1 counters on a creature you control.
Draw two cards.

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.

({T}: Add {U} or {R}.)
As Ritzy Parlor enters, you may pay {1}. If you don't, Ritzy Parlor enters tapped.

{T}, Pay 1 life: Add {W}.
{6}{W}{W}{W}, Exile Rius, Temple of the Grandfather from your hand: Target player gains 20 life.

Riv's Safehouse enters tapped.
When Riv's Safehouse enters, you may mill two cards.
{T}: Add {U} or {B}.

As long as your deck contains only blue and colorless cards, your minimum deck size is reduced by eight.

River's Wrath deals 2 damage to any target. If you've been dealt damage this turn, River's Wrath deals 4 damage instead.

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

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.

Return target creature or land card from your graveyard to your hand.

Look at the top five cards of your library. You may reveal a land or enchantment card from among them and put it into your hand. Then put the rest on the bottom of your library in any order.

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

Flash
Enchant creature
When Roar of the Wilds enters, enchanted creature gets +3/+3 until end of turn.
When enchanted creature dies, create a 1/1 green Saproling creature token.

({T}: Add {U} or {R}.)
Roaring Cascade enters tapped.

Enchant creature
Enchanted creature gets +2/+1 and is a black Zombie in addition to its other colors and types.

Search your library for up to two basic land cards and put them onto the battlefield tapped, then shuffle.
Fuse (You may cast one or both halves of this card from your hand.)

When Rod of Marble Row enters, you may return target creature to its owner's hand.
Equipped creature gets +1/+1.
Equip {1}

Roggar's Frenzy deals 3 damage to any target.
{2}{R}, Exile Roggar's Frenzy from your graveyard: Create two tapped 1/1 red Elemental creature tokens.

Roggar's Gambit deals 2 damage to any target.
Reprise {1}{R} (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.)
Damage dealt by sources reprising Roggar's Gambit can't be prevented.

Choose one —
• Destroy target artifact.
• Target creature gets +2/+1 and gains first strike until end of turn.
Kindle 2—{3}{R} ({3}{R}, Exile this card from your graveyard: Create two 1/1 colorless Elemental creature tokens. Kindle only as a sorcery.)

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

Enchant creature
Enchanted creature can't be blocked.
Whenever enchanted creature deals combat damage to a player, you may aetherize it. (To aetherize, create a token that's a copy of it, then exile that token.)