Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for .)

Whenever a nontoken artifact you control is put into a graveyard from the battlefield, create a 1/1 colorless Servo artifact creature token.

When Smelt-Ward Gatekeepers enters the battlefield, if you control two or more Gates, gain control of target creature an opponent controls until end of turn. Untap that creature. It gains haste until end of turn.

Players can't untap more than one creature during their untap steps.

(: Add or .)

Smoldering Marsh enters the battlefield tapped unless you control two or more basic lands.

Flying

Whenever Smuggler's Copter attacks or blocks, you may draw a card. If you do, discard a card.

Crew 1 (Tap any number of creatures you control with total power 1 or more: This Vehicle becomes an artifact creature until end of turn.)

Whenever you cycle a card, tap target creature an opponent controls.

Flying

When you draw your third card in a turn, return Sneaky Snacker from your graveyard to the battlefield tapped.

Tap up to two target creatures. Those creatures don't untap during their controller's next untap step.

Draw two cards, then discard a card.

(: Add or .)

Snowfield Sinkhole enters the battlefield tapped.

Soaring Seacliff enters the battlefield tapped.

When Soaring Seacliff enters the battlefield, target creature gains flying until end of turn.

: Add .

Solar Transformer enters the battlefield tapped.

When Solar Transformer enters the battlefield, you get (three energy counters).

: Add .

, Pay : Add one mana of any color.

Soldevi Golem doesn't untap during your untap step.

At the beginning of your upkeep, you may untap target tapped creature an opponent controls. If you do, untap Soldevi Golem.

: Add . Activate only once each turn. (While activating an ability, use rather than tapping the permanent to pay for .)

When Solitary Sanctuary enters the battlefield, tap target creature an opponent controls and put a stun counter on it. (If a permanent with a stun counter would become untapped, remove one from it instead.)

Whenever you tap an untapped creature an opponent controls, put a +1/+1 counter on target creature you control.

When Solstice Zealot enters the battlefield, you get (two energy counters).

, Pay : Tap target creature.

Flying

Whenever Somnophore deals damage to a player, tap target creature that player controls. That creature doesn't untap during its controller's untap step for as long as Somnophore remains on the battlefield.

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn.

: Add one mana of any color.

, : Untap another target artifact.

, : Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

, : Target creature can't be blocked this turn.

As Soporific Springs enters the battlefield, you may pay 3 life. If you don't, it enters the battlefield tapped.

: Add .

Whenever Soul of Windgrace enters the battlefield or attacks, you may put a land card from a graveyard onto the battlefield tapped under your control.

, Discard a land card: You gain 3 life.

, Discard a land card: Draw a card.

, Discard a land card: Soul of Windgrace gains indestructible until end of turn. Tap it.

First strike, vigilance

Concealed Position — When Space Marine Scout enters the battlefield, if an opponent controls more lands than you, you may search your library for a Plains card, put it onto the battlefield tapped, then shuffle.

Spare Supplies enters the battlefield tapped.

When Spare Supplies enters the battlefield, draw a card.

, , Sacrifice Spare Supplies: Draw a card.

When Sparring Regimen enters the battlefield, learn. (You may reveal a Lesson card you own from outside the game and put it into your hand, or discard a card to draw a card.)

Whenever you attack, put a +1/+1 counter on target attacking creature and untap it.

Spawning Pool enters the battlefield tapped.

: Add .

: Spawning Pool becomes a 1/1 black Skeleton creature with ": Regenerate this creature" until end of turn. It's still a land. (If it regenerates, the next time it would be destroyed this turn, it isn't. Instead tap it, remove all damage from it, and remove it from combat.)

Whenever Spectral Bears attacks, if defending player controls no black nontoken permanents, it doesn't untap during your next untap step.

Trample

Whenever Spectral Force attacks, if defending player controls no black permanents, it doesn't untap during your next untap step.

Enchant creature

Enchanted creature doesn't untap during its controller's untap step.

When enchanted creature becomes the target of a spell, sacrifice Spectral Prison.

When Spelunking enters the battlefield, draw a card, then you may put a land card from your hand onto the battlefield. If you put a Cave onto the battlefield this way, you gain 4 life.

Lands you control enter the battlefield untapped.

Flying

At the beginning of your postcombat main phase, there is an additional beginning phase after this phase. (The beginning phase includes the untap, upkeep, and draw steps.)

Flying

Inspired — Whenever Sphinx's Disciple becomes untapped, draw a card.

Spikefield Cave enters the battlefield tapped.

: Add .

Hideaway 4 (When this land enters the battlefield, look at the top four cards of your library, exile one face down, then put the rest on the bottom in a random order.)

Spinerock Knoll enters the battlefield tapped.

: Add .

, : You may play the exiled card without paying its mana cost if an opponent was dealt 7 or more damage this turn.

Visit — Tap target creature an opponent controls.

Lights — 2, 3, 6

Visit — Tap target creature an opponent controls.

Lights — 2, 5, 6

Spire Garden enters the battlefield tapped unless you have two or more opponents.

: Add or .

Spirebluff Canal enters the battlefield tapped unless you control two or fewer other lands.

: Add or .

Whenever Spireside Infiltrator becomes tapped, it deals 1 damage to each opponent.

Enchant creature

Whenever enchanted creature becomes tapped, put a -0/-2 counter on it.

Return all land cards from your graveyard to the battlefield tapped.

2 — Vigilance

4 — , : Tap target creature.

2 — 1/5

3 — 5/4

Ravenous (This creature enters the battlefield with X +1/+1 counters on it. If X is 5 or more, draw a card when it enters.)

Defender

Spore Chimney — When Sporocyst enters the battlefield, search your library for up to X basic land cards, put them onto the battlefield tapped, then shuffle.

Gain control of target creature you don't control until end of turn. Untap that creature. It gains haste until end of turn.

Storm (When you cast this spell, copy it for each spell cast before it this turn. You may choose new targets for the copies.)

When Springbloom Druid enters the battlefield, you may sacrifice a land. If you do, search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.

, Tap an untapped creature you control: Add one mana of any color.

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for or one mana of that creature's color.)

Buyback (You may pay an additional as you cast this spell. If you do, put this card into your hand as it resolves.)

Create a 1/1 green Saproling creature token.

Spur Grappler gets +2/+1 as long as you control no untapped lands.

Spymaster's Vault enters the battlefield tapped unless you control a Swamp.

: Add .

, : Target creature you control connives X, where X is the number of creatures that died this turn. (Draw X cards, then discard X cards. Put a +1/+1 counter on that creature for each nonland card discarded this way.)

Haste

Whenever Squee, Dubious Monarch attacks, create a 1/1 red Goblin creature token that's tapped and attacking.

You may cast Squee, Dubious Monarch from your graveyard by paying and exiling four other cards from your graveyard rather than paying its mana cost.

2 — Ward (Whenever this permanent becomes the target of a spell or ability an opponent controls, counter it unless that player pays .)

4 — Provoke (Whenever this creature attacks, you may have target creature defending player controls untap and block it if able.)

3 — 5/3

5 — 7/7

, Pay 1 life: Destroy target permanent you own.

, Pay 2 life: Add one mana of any color.

, Pay 3 life: Proliferate.

, Pay 4 life: Draw a card.

: Untap Staff of Compleation.