msem-instigator

Equipped creature gets +1/+3.
Whenever another creature blocks or becomes blocked by equipped creature, that creature loses all abilities until end of turn.
Equip {3}

Vigorbreath Scourge enters with X +1/+1 counters on it.
Whenever Vigorbreath Scourge attacks, it gets +X/+X until end of turn, where X is your devotion to green. Then if its power is 6 or greater, draw a card. (Each {G} in the mana costs of permanents you control counts toward your devotion to green.)

Whenever you attack, create an X/X red Elemental creature token that's tapped and attacking, where X is the number of attacking creatures.
Fleeting {1}{R} (You may cast this spell for its fleeting cost. If you do, sacrifice it at the beginning of the next end step.)

{2}{G}, {T}: Another target creature you control gets +2/+2 until end of turn.

Alpha (You may have this creature enter with a +1/+1 counter on it. If you do, it becomes alpha and can only attack alone.)
Vigilance

Kicker {1}{G} (You may pay an additional {1}{G} as you cast this spell.)
When Vigorous Tracker enters, if it was kicked, search your library for a land card, reveal it, put it into your hand, then shuffle.

[+1]: Each player discards a card or sacrifices a creature.
[–3]: Vikalden deals X damage to any target and you gain X life, where X is the number of Swamps you control.
[–5]: You get an emblem with “{B}, Pay 2 life: Draw a card.”

When Viking Greataxe enters, attach it to target creature you control.
Equipped creature gets +2/+1.
Equip {3}

Dominance — When Viking Packleader enters, create a 2/2 green Wolf creature token if you control the creature with the greatest power or tied for the greatest power.

Whenever you cast a spell during an opponent's turn, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

When Vile Progenitor enters, create a 3/2 colorless Horror creature token.
As long as you control five or more lands, Horrors you control get +1/+1 and have trample.
Evoke {1}{G} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

When Vile Weavers enters, if you control an enchantment, target player loses 3 life.

When Village Courier enters, look at the top four cards of your library. You may reveal an artifact, enchantment, or land card from among them and put it into your hand. Put the rest on the bottom of your library in any order.

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
Whenever a creature you control enters, each opponent loses 1 life.
I, II — Create a 1/1 black Actor creature token with lifelink.
III — Each opponent loses life equal to the number of tokens you control. You gain life equal to the life lost this way.

Whenever one or more creatures die for the first time each turn, you draw a card and you lose 1 life.
Whenever you cast a black noncreature spell, Villainy deals 2 damage to any target and you gain 2 life.

Tithe (When this creature enters, you may tap three other artifacts and/or creatures you control.)
When Vindictive Abbot enters, you may have target creature get -1/-1 until end of turn. If Vindictive Abbot's tithe was paid, destroy that creature.

Rhapsody {3}{R}{R} (Pay {3}{R}{R} to cast this as a 4/4, or as a sorcery to make it become a 4/4.)
Whenever Vindictive Guardian or another creature you control enters, if that creature's power is 4 or greater, create a Treasure token.

Whenever Vindictive Pyromancer perseveres, it deals 1 damage to any other target. (A creature perseveres when it survives damage.)

Flying, lifelink
Whenever a creature you control dies, Vindictive Regent gets +1/+1 until end of turn.
At the beginning of your end step, if you gained 3 or more life this turn, each opponent sacrifices a creature.

As long as Vinehorn Stag has a +1/+1 counter on it, it can't be blocked by more than one creature.

Enchant creature
Whenever enchanted creature becomes tapped, Violent Repercussions deals 3 damage to that creature's controller.

When Viork Woods Butcher enters, if you control another Warrior, target opponent loses 2 life.

Menace
Whenever a player gains life, that player sacrifices a permanent.

First mate—Your starting deck contains one or more cards of exactly each color and each color pair. (If this card outside the game is your chosen first mate, you may swap it with a card in your opening hand.)
During each of your turns, you may cast a card of each color from your graveyard. If a spell cast this way would be put into your graveyard, exile it instead.