msem-instigator

Each player chooses three permanents they control, then returns the others to their owners' hands. Each player loses all unspent mana.
Exile Turn the Record Over.

When Twisted Predator dies, you draw a card and you lose 1 life.

{1}, Sacrifice another creature: Crystallize. Activate only as a sorcery. (Put a +1/+1 counter on a creature you control or create a Treasure.)
{W}{U}{B}{R}{G}: Target creature gets +3/+3 and gains trample until end of turn. Activate only as a sorcery.

Flash
When Twisted Speaker enters, return target spell to its owner's hand. That spell's controller loses 2 life.

Cast this spell only if you control a creature.
Exile all creatures.

Whenever a Wizard you control deals damage to a player, draw a card.

Whenever Uncanny Allocator enters or attacks, give any number of permanents and/or players with counters on them another counter of each kind already there.

Unceasing Flames deals X damage to any target, where X is 2 plus the number of cards named Unceasing Flames in your graveyard.
Conjure three cards named Unceasing Flames and shuffle them into your main library.

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.

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

Create three 1/1 colorless Servo artifact creature tokens.
Exile Unending Armies. At the beginning of your upkeep, if you have more life than each opponent, you may cast it without paying its mana cost. Otherwise, put it into your graveyard.

Enchant land
When Unexplored Regions enters, draw a card.
Enchanted land is an artifact in addition to its other types and has “{T}: Add one mana of any color.”

If you would draw a card, you may return an instant or sorcery card from your graveyard to your hand instead.
{U}: Draw three cards.

Each artifact you control has all the activated abilities of other artifacts you control.

Lifelink
Augmented — Whenever you cast a spell, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, put a +1/+1 counter on United Guardian. It loses this ability and gains “Whenever United Guardian attacks, create two 1/1 blue Elemental creature tokens with flying that are tapped and attacking.”

Cadence (Whenever you cast a spell, if its mana value is greater than this creature's power, put a +1/+1 counter on this creature.)
United Patrol can block an additional creature each combat.

When Unity Spheres enters, create two 1/1 colorless Construct artifact creature tokens.
Tap two untapped creatures you control: Add two mana of any one color.

Rhapsody {4}{U}{U} (Pay {4}{U}{U} to cast this as a 4/4, or as a sorcery to make it become a 4/4.)
When Unstable Prophet enters, surveil X, where X is its power. (Look at the top X cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Whenever Unstable Vein enters or leaves the battlefield, choose one —
• Put a +1/+1 counter on each of up to two target creatures.
• Unstable Vein deals 2 damage to target creature with flying.

Cadence (Whenever you cast a spell, if its mana value is greater than this creature's power, put a +1/+1 counter on this creature.)

Rhapsody {4}{R}{W} (Pay {4}{R}{W} to cast this as a 4/4, or as a sorcery to make it become a 4/4.)
Lifelink, haste

Whenever V-4 Fixit or another artifact you control enters, target creature you control gets +1/+1 until end of turn.

Counter target spell unless its controller pays {3}.

Choose one—
• Destroy target permanent with mana value 2.
• Return target permanent card from a graveyard to its owner's hand.
Exile Veil's Recovery.

{B}: Veilborn Hunter gets +1/+1 until end of turn.
Sacrifice another creature: Veilborn Hunter gains indestructible until end of turn. Tap it.