msem-instigator

{T}, Pay 1 life: Add {U} or {B}.
{1}, {T}, Sacrifice Unlit Alley: Investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

Gain control of target nonland permanent if you control a permanent with a greater mana value. Otherwise, destroy that permanent.

{6}{W}: Tap all creatures target player controls.

Choose one, then choose another for each card named Unraveling in your graveyard.
• Counter up to one target spell.
• Scry 2, then draw a card.
• Up to three target lands your opponents control don't untap during their controller's next untap step.
• Creatures your opponents control get -4/-0 until end of turn.

Unreflected Cultist can't be blocked by Reflections.

Choose one, then choose another for each card named Unrelenting in your graveyard.
• Creatures get -1/-1 until end of turn.
• Create a 2/2 blue Elemental creature token.
• Each opponent loses 3 life and you gain 3 life.
• Search your library for a card with mana value 4 or greater, reveal it, put it into your hand, then shuffle.

Experience (Whenever this creature attacks, if it has fewer than three +1/+1 counters on it, put a +1/+1 counter on it.)
Unstoppable Weed gets +1/+1 for each +1/+1 counter on other creatures you control.

Choose one, then choose another for each card named Unsuspecting in your graveyard.
• You may return a permanent you control to its owner's hand.
• You may put an artifact, creature, or land card with mana value 2 or less from your hand onto the battlefield.
• Untap up to three target permanents.
• You gain 4 life.

For each land you control, you may return a land card from your graveyard to the battlefield tapped.

Untrekked Territory enters the battlefield tapped.
{T}: Add {B} or {G}.
When Untrekked Territory enters the battlefield, you may put a loyalty counter on a planeswalker you control.

Look at target opponent's hand, then fateseal 1. (To fateseal 1, look at the top card of an opponent's library, then you may put it on the bottom of that player's library.)

Gain control of target creature until end of turn. Untap that creature. It gains haste and is marked until end of turn.

All creatures have “When this creature enters the battlefield, destroy target creature with a lesser mana value.”

({T}: Add {B} or {R}.)
Urban Wastelands enters the battlefield tapped.
Cycling {2} ({2}, Discard this card: Draw a card.)

{4}{B}{B}: Return Urchin Defector from your graveyard to the battlefield transformed.

Menace

Flash
Death knell — Put a +1/+1 counter on each creature you control. (As a creature you control dies, trigger one death knell of that creature or another permanent you control.)

Advance {6}{W}{W} (Cast this for {6}{W}{W} to advance it as it enters. {6}{W}{W}: Advance this as a sorcery.)
Flying, vigilance, lifelink
Whenever Valera, Constructed Angel advances, destroy all nonartifact creatures.

Whenever Valinov Collector or another artifact enters the battlefield under your control, Valinov Collector deals 2 damage to each opponent and you gain 2 life.

Advance {4}{B}{B} (Cast this for {4}{B}{B} to advance it as it enters. {4}{B}{B}: Advance this as a sorcery.)
Flying
Whenever Valinov Siphoner advances, target player loses 2 life and you gain 2 life.

Advance {3}{R}{W}{B} (Cast this for {3}{R}{W}{B} to advance it as it enters. {3}{R}{W}{B}: Advance this as a sorcery.)
Whenever Valinov Vandal advances, target opponent sacrifices a permanent. Put a +1/+1 counter on Valinov Vandal.

Vampire Partaker can't block.
Sacrifice a creature: Put a +1/+1 counter on Vampire Partaker. You gain 1 life. Activate only as a sorcery.

Target creature gets +2/+2 and gains indestructible until end of turn.

Enchant creature
When Vampiric Rise enters the battlefield, fateseal 2. (To fateseal 2, look at the top two cards of an opponent's library, then put any number of them on the bottom of that player's library and the rest on top in any order.)
Enchanted creature gets +1/+0 and has flying.

Lifelink
Whenever a creature enters the battlefield from a graveyard, gain control of that creature.