msem-instigator

Walker of the Final Path gets +3/+3 and has trample as long as you control a Horror.
When Walker of the Final Path enters, search your library for a Revelation card, put it into your graveyard, then shuffle.

When Walking Armory enters, return all Equipment cards from your graveyard to the battlefield, then attach them to Walking Armory.

{2}, Sacrifice Walking Platform: Create a 1/1 colorless Thopter artifact creature token with flying.

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 Ivy enters, create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)

Defender, reach

At the beginning of your end step, draw two cards and you lose 2 life.

Search your library for a Forest or Academy card, put it onto the battlefield tapped, then shuffle.

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

{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.

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.

Flash
Whenever a permanent with an Adventure you control enters, put a +1/+1 counter on Wandering Dingo.

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.

Wandering Megaflora has hexproof as long as it's untapped.
Whenever Wandering Megaflora attacks, untap another target creature you control.

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

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 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, 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.)

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.

{T}: Add {C}.
{5}, {T}, Sacrifice War Golem Forge: Create a 3/3 colorless Golem artifact creature token.

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.)

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.