msem-instigator

Crew 1 (Tap any number of creatures you control with total power 1 or greater: This Vehicle becomes an artifact creature until end of turn.)
Whenever Scavengermobile deals combat damage to a player, choose land or nonland, then rediscover a card of that kind. (Look at the top card of your library. You may reveal it and put it into your hand if it's a card of the chosen type. Otherwise, put it back or into your graveyard.)

Flying
{1}{U}, Sacrifice Scholar's Assistant: Draw a card.

Target creature you control gets +1/+2 until end of turn. If that creature is white, create a white Aura enchantment token with enchant creature and “Enchanted creature has first strike” attached to that creature.

Scorch deals 3 damage to any target.

As Scorched Copse enters, you may tap an untapped creature you control. If you don't, Scorched Copse enters tapped.
{T}: Add {R} or {G}.

Enchant creature
Enchanted creature gets +2/-2.

Whenever you cast a spell, Scorned Figurant gets +1/+1 until end of turn.

Scoundreleo enters with a +1/+1 counter on it if a creature you controlled dealt combat damage to a player this turn.

Scoured Barrens enters tapped.
When Scoured Barrens enters, you gain 1 life.
{T}: Add {W} or {B}.

Scoured Mesa enters tapped.
{T}: Add {W}.
Desertcycling {1}{W} ({1}{W}, Discard this card: Search your library for a Desert card, reveal it, and put it into your hand, then shuffle.)

Double strike
Creatures you control have trample.
Excess noncombat damage that would be dealt by sources you control to permanents an opponent controls is dealt to that player instead.

Look at the top five cards of your library. You may reveal a Scout or land card from among them and put it into your hand. Put the rest on the bottom of your library in any order.

Prevent all damage that would be dealt by creatures this turn.

Target player discards a card. If they didn't discard an artifact card, you gain 3 life.

Look at the top X cards of your library, where X is the number of instant and sorcery cards in your graveyard. You may reveal an instant or sorcery card from among them and put it on top of your library. Then put the rest on the bottom of your library in a random order.

Scrounging Dunes enters tapped.
{T}: Add {W} or {B}.
{1}{W}{B}: Until end of turn, Scrounging Dunes becomes a Wurm creature with lifelink in addition to its other types.
Scavenge {1}{W}{B}

{2}{B}, {T}, Sacrifice Sculler's Oar: Return up to two target creature cards from your graveyard to your hand.

Sculpted Observatory enters tapped.
{T}: Add {W} or {U}.
{1}, {T}: Add one mana of any color.

Until end of turn, target creature gains “When this creature is dealt damage, destroy it.” (Then exile this card. You may cast the creature later from exile.)

At the beginning of your upkeep, if six or more cards are in your graveyard, you may transform Scuttling Gnat.

Sea Of Skies Beyond enters tapped.
Whenever you cast a noncreature spell, put a creation counter on Sea Of Skies Beyond.
{T}, Remove ten creation counters from Sea Of Skies Beyond and sacrifice it: Shuffle your hand into your library, then draw five cards.

Concord — {1}{G}: Until end of turn, Seadrake Rider gets +2/+3 and must be blocked if able. Activate only during your turn, only once each turn, and only if there are four or more card types among permanents you control.

Seafoam Slasher gets +1/+1 and has deathtouch as long seven or more cards are in your graveyard.
Cycling {2} ({2}, Discard this card: Draw a card.)

Golden age (If you cast an instant or sorcery spell, activated a nonmana ability, and attacked this turn, enter a renaissance for this game.)
Target creature or planeswalker an opponent controls phases out. If you're in a renaissance, exile it instead.

Choose target card in a graveyard other than a basic land card. Search its owner's graveyard, hand, and library for any number of cards with the same name as that card and exile them. Then that player shuffles.
Scry 1.