When Seekers' Squire enters, it explores. (Reveal the top card of your library. Put that card into your hand if it's a land. Otherwise, put a +1/+1 counter on this creature, then put the card back or put it into your graveyard.)

Destroy target land. Add .

As long as you control a Plains, Sejiri Merfolk has first strike and lifelink. (Damage dealt by a creature with lifelink also causes its controller to gain that much life.)

Whenever another nontoken creature you control dies, create a 3/1 black and red Graveborn creature token with haste.

: Add or .

: Selesnya Keyrune becomes a 3/3 green and white Wolf artifact creature until end of turn.

When Selkie Hedge-Mage enters, if you control two or more Forests, you may gain 3 life.

When Selkie Hedge-Mage enters, if you control two or more Islands, you may return target tapped creature to its owner's hand.

Flying

Whenever another creature dies, put two +1/+1 counters on Sengir, the Dark Baron.

Whenever another player loses the game, you gain life equal to that player's life total as the turn began.

Partner (You can have two commanders if both have partner.)

Defender

At the beginning of combat on your turn, you may clash with an opponent. If you win, Sentry Oak gets +2/+0 and loses defender until end of turn. (Each clashing player reveals the top card of their library, then puts that card on the top or bottom. A player wins if their card had a higher mana value.)

You may pay and tap four untapped creatures you control with flying rather than pay this spell's mana cost.

Flying, lifelink

Other creatures you control with flying have indestructible. (Damage and effects that say "destroy" don't destroy them.)

Whenever Serpentine Basilisk deals combat damage to a creature, destroy that creature at end of combat.

Morph (You may cast this card face down as a 2/2 creature for . Turn it face up any time for its morph cost.)

Devoid (This card has no color.)

Serpentine Spike deals 2 damage to target creature, 3 damage to another target creature, and 4 damage to a third target creature. If a creature dealt damage this way would die this turn, exile it instead.

: Put a -1/-1 counter on Serrated Biskelion and a -1/-1 counter on target creature.

Whenever Serum Tank or another artifact enters, put a charge counter on Serum Tank.

, , Remove a charge counter from Serum Tank: Draw a card.

When Setessan Starbreaker enters, you may destroy target Aura.

Exile all attacking creatures target player controls. That player may search their library for that many basic land cards, put those cards onto the battlefield tapped, then shuffle.

Choose target creature. If it's attacking, it can't be blocked this turn. If it's blocking, prevent all combat damage that would be dealt this combat by it and each creature it's blocking.

Partner with Brallin, Skyshark Rider

Flying

Whenever you draw a card, put a +1/+1 counter on Shabraz, the Skyshark and you gain 1 life.

: Target Human gains flying until end of turn.

Flying

Shacklegeist can block only creatures with flying.

Tap two untapped Spirits you control: Tap target creature you don't control.

Gain control of target creature until end of turn. Untap that creature. Until end of turn, it gains haste and "Whenever this creature deals damage, destroy target Equipment attached to it."

Flash

At the beginning of your upkeep, each player mills three cards. You may exile a creature card from among the cards milled this way. If you do, Shadow Kin becomes a copy of that card, except it has this ability.

, , Sacrifice another creature: Draw X cards, where X is that creature's power.

Choose a Background (You can have a Background as a second commander.)

Shake the Foundations deals 1 damage to each creature without flying.

Draw a card.

Trample

Whenever Shaleskin Bruiser attacks, it gets +3/+0 until end of turn for each other attacking Beast.

: The next 1 damage that would be dealt to Shaman en-Kor this turn is dealt to target creature you control instead.

: The next time a source of your choice would deal damage to target creature this turn, that damage is dealt to Shaman en-Kor instead.

Exile target creature card from a graveyard. Create a 2/2 black Zombie creature token. You gain 2 life.

Equipped creature gets +1/+0.

Whenever equipped creature attacks, you may mill two cards.

Equip (: Attach to target creature you control. Equip only as a sorcery.)

Activated abilities of lands your opponents control can't be activated unless they're mana abilities.

Sharkey, Tyrant of the Shire has all activated abilities of lands your opponents control except mana abilities.

Mana of any type can be spent to activate Sharkey's abilities.

Equipped creature has first strike.

As long as equipped creature is a Human, it gets +1/+1.

Equip

Each player who controls a creature with power 4 or greater draws a card. Then destroy all creatures.

Kicker

Trample, haste

If Shatterskull Charger was kicked, it enters with a +1/+1 counter on it.

At the beginning of your end step, if Shatterskull Charger doesn't have a +1/+1 counter on it, return it to its owner's hand.

This spell costs less to cast for each creature in your party. (Your party consists of up to one each of Cleric, Rogue, Warrior, and Wizard.)

Haste

Shatterskull Smashing deals X damage divided as you choose among up to two target creatures and/or planeswalkers. If X is 6 or more, Shatterskull Smashing deals twice X damage divided as you choose among them instead.

Flying

Shauku, Endbringer can't attack if there's another creature on the battlefield.

At the beginning of your upkeep, you lose 3 life.

: Exile target creature and put a +1/+1 counter on Shauku.

Target creature gets +2/+2 until end of turn. You may remove a -1/-1 counter from it.

: Target creature loses all "bands with other" abilities until end of turn.

: Target blue creature gains shroud until end of turn. (It can't be the target of spells or abilities.)

(: Add or .)

Sheltered Thicket enters tapped.

Cycling (, Discard this card: Draw a card.)

, Sacrifice a creature: Target creature gets +3/+3 until end of turn.

Equipment named Sword of Kaldra, Shield of Kaldra, and Helm of Kaldra have indestructible.

Equipped creature has indestructible. (Damage and effects that say "destroy" don't destroy it.)

Equip

, , Return Shigeki, Jukai Visionary to its owner's hand: Reveal the top four cards of your library. You may put a land card from among them onto the battlefield tapped. Put the rest into your graveyard.

Channel — , Discard Shigeki: Return X target nonlegendary cards from your graveyard to your hand.

, : All damage that would be dealt to you this turn by target attacking creature is dealt to Shimian Night Stalker instead.

Flying

Cycling (, Discard this card: Draw a card.)

: Add .

, : Target legendary creature gains first strike until end of turn.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

When this creature enters, return target instant or sorcery card from your graveyard to your hand.

Shipwreck Marsh enters tapped unless you control two or more other lands.

: Add or .

Defender

As long as an artifact entered the battlefield under your control this turn, Shipwreck Sentry can attack as though it didn't have defender.

Flying

: Target creature an opponent controls attacks this turn if able.

, : Attacking creatures get -1/-1 until end of turn.

Flying (This creature can't be blocked except by creatures with flying or reach.)

: Shivan Hellkite deals 1 damage to any target.

Constellation — Whenever an enchantment you control enters, you may draw a card. If you do, discard a card.

Sacrifice Shock Troops: It deals 2 damage to any target.