Surface {U}. Scuttling Cicada surfaces transformed.

When Sea Breeze enters, return up to one target creature to its owner's hand, then surveil 1.

When Seafloor Scavenger enters or deals combat damage to a player, you may return target exiled card with surface you own to your hand.

Look at the top two cards of your library. Put one into your hand and the other into your graveyard.
Surface {2}{U}

Flash
When Seal Away enters, exile target tapped creature an opponent controls until Seal Away leaves the battlefield.

At the beginning of each end step, create a 2/2 white and blue Seal Orb creature token if you activated two or more nonmana abilities this turn.
{W}{U}: Scry 1. You gain 1 life.

Target player reveals their hand. You may choose a nonland card from it. If you do, that player discards that card. Otherwise, draw a card.

Scry 3, then reveal the top card of your library. If it's a creature card, put it into your hand.

This spell costs {2} less to cast if you've activated a nonmana ability this turn.
Searing Grace deals 3 damage to any target.

Vigilance
When Seasoned Spymaster enters, teach target creature vigilance.

Lifelink
Whenever Secluded Gorgon dies, you may bless target creature.

Secluded Hangar enters tapped unless you control a basic non-Forest land.
{T}: Add {G}.
{2}, {T}: Put a +1/+1 counter on target creature that entered this turn.

Exile all creatures you don't control. Then return those cards to the battlefield tapped under their owners' control unless you've cast another spell named Second Crown's Fall this game. Then exile Second Crown's Fall.

Flash
When Security Initiative enters, you may tap or untap target nonland permanent. Then draw a card.
An opponent controls three or more tapped nonland permanents.

Flying
Whenever Seeker Orbs becomes tapped, scry 1.

Whenever a basic land you control enters, put a +1/+1 counter on Seeker of New Horizons. If you control seven or more lands, bless that land.

Whenever a land you control enters, scry 1. If that land is a Ruin, scry 2 instead.

When Seer of the Aspirants enters, surveil 1.
Wander {2}{G}

Trample
When Seismic Chimera enters, bless target creature.

Vigilance
Whenever Selective Truthseeker or another nontoken creature you control enters, surveil 1. When you put a nonland card into your graveyard this way, you gain 1 life.

Vigilance
{1}, {T}: Tap target creature.

Approval — When Senators' Chauffeur enters, return up to one target creature card with mana value less than or equal to the number of colors among permanents you control from your graveyard to the battlefield.

Serpentine Woods enters tapped.
{T}: Add {B} or {G}.
{2}{B}{G}, {T}, Sacrifice Serpentine Woods: Draw a card.

{B}, Sacrifice Serrated Fossil: Choose a nonland card name. Target player reveals their hand and discards a card with that name if able. Activate only as a sorcery.
Surface {3}{B}{B}. Serrated Fossil surfaces transformed.

Whenever a nontoken creature you control dies, create a token that's a copy of it, except it's a Minion and has decayed.