msem-instigator

Create a 2/1 red and white Fox creature token. If you're attacking, that token enters tapped and attacking.
Showcase {4}{R} (Then if you cast this for its showcase cost, create a 1/1 red Bard creature token that can't block and exile this. Whenever it attacks, you may cast a free copy of this.)

WZ-18 Troublemaker enters with a +1/+1 counter on it.
When WZ-18 Troublemaker dies, put its counters on target creature you control.
{1}{R}, Exile WZ-18 Troublemaker from your graveyard: It deals 2 damage to each opponent.

Wake of the Beast deals 2 damage divided as you choose among one or two targets.
Whenever a creature you control becomes monstrous, you may pay {R}. If you do, return Wake of the Beast from your graveyard to your hand.

Whenever Wandering Conqueror attacks, it explores. (Reveal the top card of your library. Put it into your hand if it's a land. Otherwise, put a +1/+1 counter on this creature, then you may put that card in your graveyard.)
As Wandering Conqueror explores a land, you may put that card into your graveyard. Whenever you do, Wandering Conqueror deals 2 damage to target player or planeswalker.

Whenever Wandering Doyen is dealt damage, it deals that much damage to you.
{4}{R}: Attacking creatures you control get +1/+0 and gain first strike until end of turn.

Menace (This creature can't be blocked except by two or more creatures.)
{1}{R}: Wandering Goliath gets +1/+0 until end of turn.

Survivors you control have menace.

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

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.)

Legacy (You may play this side of this card only from your graveyard. Exile it if it would leave the battlefield or not resolve.)
Whenever you attack, you may discard up to X cards, where X is the number of attacking creatures you control. Draw a card for each card discarded this way.

Creatures you control get +1/+0 and gain haste until end of turn. (Cast a copy of this spell once while this creature is on the battlefield.)

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I, II — War's Sorrow deals 1 damage to any target.
III — Each player sacrifices another permanent. Put War's Sorrow on top of its owner's library unless a player has it deal 3 damage to them.

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

Haste
Glorious end — When Warband Lieutenant dies, if it was tapped, put a +1/+1 counter on another target creature you control.

Flying, haste
Whenever Warfury Dragon becomes enchanted or equipped, monstrosity 2. (If this creature isn't monstrous, put two +1/+1 counters on it and it becomes monstrous.)

Trample
Warlord of Wun Su can't block alone.

Each instant and sorcery card in your graveyard gains agonize until end of turn.
Agonize (You may cast this card from your graveyard by putting a -1/-1 counter on a creature you control in addition to paying its other costs. Then exile this card.)

Creatures you control get +1/+0 and attack each turn if able.
As long as you control four or more Mountains, attacking creatures you control get an additional +1/+0 and have first strike.

You may put a Dragon creature card from your hand onto the battlefield. That creature gains haste until end of turn. Return it to its owner's hand at the beginning of the next end step.

Trample, prowess
You may exert Wartorn Veteran as it attacks. When you do, double its power until end of turn. (An exerted creature won't untap during your next untap step.)

Haste
When Wasteland Rabblerousers enters, creatures your opponents control with power X or less can't block this turn, where X is the number of Deserts you control.

First strike
Wither (This deals damage to creatures in the form of -1/-1 counters.)

Trample, haste
Defiance (Whenever this creature takes damage, if it survives and wasn't defiant, put a +1/+1 counter on it and it becomes defiant.)
Whenever Wastewolf attacks, it deals 1 damage to any other target.

Whenever Watchkeeper Deserter attacks, discard up to two cards, then draw that many cards. Watchkeeper Deserter gets +X/+0 until end of turn, where X is the total mana value of the discarded cards.

Watchkeeper's Retort deals 2 damage to target creature or planeswalker. Scry 1. (To scry 1, look at the top card of your library. You may put that card on the bottom of your library.)