msem-instigator

Overcast — Whenever you cast a spell, create a 1/1 black Bird creature token with flying and menace if {C} was spent to cast it.
Whenever three or more creatures you control deal combat damage to a player, return target card from your graveyard to your hand.

{T}: Add {B}.
{B}, {T}: Target creature gains menace until end of turn.

Whenever another non-Zombie creature you control dies, create a tapped 2/2 black Zombie creature token.
{B}, Sacrifice a creature: Target creature gains deathtouch until end of turn.

Whenever Wadepool Frog attacks, it gains flying until end of turn.

Flying
Wailing Soul has hexproof as long as it's not attacking or blocking.

At the beginning of your upkeep, each player discards a card.
Whenever Waking Watcher attacks, if defending player has no cards in hand, it gets +3/+3 and gains menace until end of turn.

Play with the top card of your library revealed.
Spells you cast that share a creature type with the top card of your library cost {1} less to cast.

Defender
When Wall of Rime enters the battlefield, tap target creature an opponent controls. That creature doesn't untap during its controller's next untap step.

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Exile target nonland permanent you don't control until Waltz on a Nimbus leaves the battlefield.
Create a 1/1 white Soldier creature token with “This creature gets +1/+1 for each enchantment you control.”
II — Search your library for a non-Saga enchantment card and reveal it. You may cast that card. Then shuffle.

Return target creature to its owner's hand. That player can't cast spells with the same name as that creature during their next turn.

Ferocious — At the beginning of your upkeep, if you control a creature with power 4 or greater, draw a card.

Equipped creature gets +2/+1.
Whenever equipped creature attacks, create a 1/1 white Peasant creature token that's tapped and attacking.
Equip {2}

{3}, {T}, Sacrifice Wanderer's Talisman: 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.

Flash
Whenever a permanent with an Adventure enters the battlefield under your control, put a +1/+1 counter on Wandering Dingo.

Whenever you cast a spell, Wandering Precursor gets +1/+0 until end of turn for each color of mana spent to cast that spell.

Create X 1/1 white Spirit creature tokens with flying, where X is two plus the number of cards named Wandering Souls in your graveyard. Conjure three cards named Wandering Souls and shuffle them into your main library.

When Wandering Visionary enters the battlefield, draw a card.
{W}{U}{B}{R}{G}: Create a 1/1 blue Elemental creature token with flying.

Assault {G} (Whenever this attacks, if it has no +1/+1 counters on it, you may pay its assault cost to put a +1/+1 counter on it.)
Whenever a creature you control assaults, it gains indestructible until end of turn.

Vanishing 1 (This creature enters the battlefield with a time counter on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
When Waning Behemoth enters the battlefield, you may pay {X}. If you do, put X time counters on it.

Target attacking creature gains double strike until end of turn. Arm it. (Create a colorless Equipment artifact token with “Equipped creature gets +1/+0” and equip {2}, then attach it to that creature.)

Whenever War Priest of Bahet deals combat damage to a player, purge. (Exile two cards that share a type from graveyards. If you do, draw a card.)

When War of Resources enters the battlefield, recruit. (Create a 0/0 white Soldier Army creature token, then put a +1/+1 counter on each Army you control.)
Whenever a creature you control dies, each opponent loses 1 life.

War-Pride Champion can't be blocked by creatures with power 2 or less.
Stampede — Whenever War-Pride Champion and a creature with greater power attack, target creature you control gets +2/+2 until end of turn.

Glorious end — When Warband Commander dies, if it was tapped, put a +1/+1 counter on each creature you control that attacked this turn.