Have

Summon: Primal Odin

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Gungnir — Destroy target creature an opponent controls.
II — Zantetsuken — This creature gains "Whenever this creature deals combat damage to a player, that player loses the game."
III — Hall of Sorrow — Draw two cards. Each player loses 2 life.

Ether

{T}, Exile this artifact: Add {U}. When you next cast an instant or sorcery spell this turn, copy that spell. You may choose new targets for the copy.

Gloomlake Verge

{T}: Add {U}.
{T}: Add {B}. Activate only if you control an Island or a Swamp.

Silent Hallcreeper

This creature can't be blocked.
Whenever this creature deals combat damage to a player, choose one that hasn't been chosen —
• Put two +1/+1 counters on this creature.
• Draw a card.
• This creature becomes a copy of another target creature you control.

Rogue's Passage

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.

Relm's Sketching

Create a token that's a copy of target artifact, creature, or land.

Unstoppable Slasher

Deathtouch
Whenever this creature deals combat damage to a player, they lose half their life, rounded up.
When this creature dies, if it had no counters on it, return it to the battlefield tapped under its owner's control with two stun counters on it.

Feed the Swarm

Destroy target creature or enchantment an opponent controls. You lose life equal to that permanent's mana value.

Divert Disaster

Counter target spell unless its controller pays {2}. If they do, you create a Lander token. (It's an artifact with "{2}, {T}, Sacrifice this token: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.")

Cornered by Black Mages

Target opponent sacrifices a creature of their choice.
Create a 0/1 black Wizard creature token with "Whenever you cast a noncreature spell, this token deals 1 damage to each opponent."

Withering Torment

Destroy target creature or enchantment. You lose 2 life.

Swamp

Syncopate

Counter target spell unless its controller pays {X}. If that spell is countered this way, exile it instead of putting it into its owner's graveyard.

Annul

Counter target artifact or enchantment spell.

Getting

Zero Point Ballad

Destroy all creatures with toughness X or less. You lose X life. If X is 6 or more, return a creature card put into a graveyard this way to the battlefield under your control.

Singularity Rupture

Destroy all creatures, then any number of target players each mill half their library, rounded down.