msem-instigator

When Seafloor Tomb enters and when you sacrifice it, exile up to two target cards from graveyards.
{1}{B}, Sacrifice Seafloor Tomb: Draw a card.
Cycling {2} ({2}, Discard this card: Draw a card.)

When Seafloor Wreckage enters and when you sacrifice it, search your library for a basic land card, reveal it, put it into your hand, then shuffle.
{1}{G}, Sacrifice Seafloor Wreckage: Draw a card.
Cycling {2} ({2}, Discard this card: Draw a card.)

Whenever one or more cards leave your graveyard, put a +1/+1 counter on Seagraf Shamblers.

Flash
{U}, Sacrifice Seal of Approval: Counter target spell unless its controller pays {2}.

{U}, Sacrifice Seal of Insights: Look at the top four cards of your library. Put one into your hand and the rest on the bottom of your library in any order.

Another target player reveals their hand. You may choose a nonland card from it. That player discards that card.
Fuse (You may cast one or both halves of this card from your hand.)

At the beginning of your upkeep, surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)
{2}{U}{U}, Sacrifice Search for a New Land: Draw two cards.

Return target cryptic card from your graveyard to your hand. (Artifacts, enchantments, and modal spells are cryptic.)

Choose one or both —
• Exile target artifact.
• Put a -1/-1 counter on target creature.

{3}{G}: Seasoned Farmer gets +2/+2 until end of turn.

At the beginning of your upkeep, you lose 1 life and create a 1/1 white Soldier creature token with melee. (Whenever that creature attacks, it gets +1/+1 until end of turn for each opponent you attacked this combat.)

Defender (This creature can't attack.)
Adorned — Secluded Wildborn can attack as though it didn't have defender as long as it's equipped and/or enchanted.

Augmented — At the beginning of combat on your turn, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, put a +1/+1 counter on Second Wave Explorer.

Flying
Instant and sorcery spells you cast cost {1} less to cast.
{2}{U}: Target player mills two cards.

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Create a 0/4 white Wall creature token with defender.
II — Put a +1/+1 counter on up to one target creature.
III — Until your next turn, each creature you control assigns combat damage equal to its toughness rather than its power.

Create three 0/1 green Plant creature tokens.

At the beginning of combat on each of your turns, you may have target land you control become a 3/3 Elemental creature with haste until end of turn. It's still a land.
Sacrifice Seeds of New Life: Return up to two target land cards from your graveyard to your hand. Activate only as a sorcery.

Whenever you draw a card, put a quest counter on Seek Perfection.
At the beginning of each end step, if Seek Perfection has four or more quest counters on it, exile target permanent you control, then return it to the battlefield under your control.

Whenever you play a land, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)
{1}{G}{U}{R}, Sacrifice three Clues: Exile cards from the top of your library until you exile three nonland cards. You may cast any number of those cards without paying their mana costs.

When Seeker of Communions enters, choose target player. If that player is poisoned, draw a card. Otherwise, that player gets a poison counter.

Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
Whenever Seeker of Ruins deals combat damage to a player, put a +1/+1 counter on it.

Enchant creature
Enchanted creature gets +2/+2.
When Seeking Horizons is put into your graveyard from anywhere other than your library, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

Equipped creature gets +1/+1.
At the beginning of your end step, if you don't control a creature, create a 1/1 white Human creature token and attach Seeking Sword to it.
Equip {1}

Whenever you cast a noncreature spell, put a number of charge counters on Selection at Danaj equal to that spell's mana value.
At the beginning of your end step, you may remove four charge counters from Selection at Danaj. If you do, look at the top four cards of your library, put one into your hand and the rest on the bottom of your library in a random order.

Whenever you cast a spell, sacrifice a permanent and draw a card.
Exile three cards from your graveyard: Counter target noncreature spell unless its controller pays {1}.