msem-instigator

This spell costs {2} less to cast if you control a Scout.
Search your library for up to two basic land cards, reveal those cards, and put one onto the battlefield tapped and the other into your hand, then shuffle.

Uncharted Haven enters the battlefield tapped.
As Uncharted Haven enters the battlefield, choose a color.
{T}: Add one mana of the chosen color.

Hexproof
When Uncharted Leviathan enters the battlefield, target creature can't be blocked this turn.

Creatures your opponents control get -2/-0 until end of turn.
Draw a card.

Whenever a creature you control is dealt damage, put a +1/+1 counter on that creature.

Enspirit (As you cast this spell, you may exile a nonenchantment creature you control until this leaves the battlefield or fails to resolve. Reduce this spell's cost by the exiled card's mana value.)
Deathtouch

Target creature can't be blocked this turn.
Compose (Then if you cast this from your hand, exile it and create a Saga token with “III—You may cast a copy of this card from exile without paying its mana cost.”)

Look at the top two cards of your library. Put one of them into your hand, then you may have any number of players each mill three cards.

When Uncovered Idol enters the battlefield, scry 1.
{1}, Sacrifice Uncovered Idol: Put a +1/+1 counter on target creature. Activate only as a sorcery.

When Uncovered Mine enters the battlefield and at the beginning of your upkeep, return a random card from your graveyard to your hand.

When Uncovered Secrets enters the battlefield, search your library for an artifact card, reveal that card, then shuffle and put that card on top.
Concord — Creatures you control get +1/+1 as long as there are four or more card types among permanents you control.

When Undead Archivist enters the battlefield, return target instant or sorcery card from your graveyard to your hand.
Revive {5}{U} ({5}{U}, Exile this card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)

When Undead Banneret enters the battlefield, if you control a legendary creature, each opponent loses 4 life.

This spell costs {1} less to cast for each Zombie creature card in your graveyard.
When Undead Harbinger enters the battlefield, return target Zombie card from your graveyard to your hand.

Creature cards in your graveyard have revive {2}{B}{B}. ({2}{B}{B}, Exile this card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)

You may have Undecided Mimic enter the battlefield or phase in as a copy of any creature on the battlefield, except it has this ability and “{2}{U}{U}: Undecided Mimic phases out.” (Treat it and anything attached to it as though they don't exist until its controller's next turn.)

If you've scried this turn, this spell costs {2} less to cast and can't be countered.
Draw two cards.

Enchant creature
Enchanted creature gets +1/+0 and has menace. (That creature can't be blocked except by two or more creatures.)

Enchant land you control
Whenever enchanted land is tapped for mana, it produces an additional mana of that type.
{1}{G}, Sacrifice Under Untamed Skies: Destroy target creature with flying.

At the beginning of each opponent's upkeep, that player may discard their hand. If the player does, sacrifice Under the Gun. Otherwise, put a bullet counter on Under the Gun, then that player loses life equal to the number of bullet counters on it.

Concord — As long as there are four or more card types among permanents you control, you may cast the first spell you cast each turn without paying its mana cost.

Mark (Whenever this creature attacks, mark target creature until end of turn.)
Undercity Diplomat can't be blocked by marked creatures.

{T}, Sacrifice a permanent: Investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)

This spell costs {1} less to cast for each artifact you control. (This applies before Treasures are sacrificed for mana.)
When Underhanded Deal enters the battlefield, draw three cards.
Whenever you cast a spell, you lose 1 life.