msem-instigator

Defender
Whenever Slumbering Bear is dealt damage, put a +1/+1 counter on it.
Remove a +1/+1 counter from Slumbering Bear: It can attack as though it didn't have defender this turn.

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)
Slums Thug gets +1/+1 and has menace as long as you've gained life this turn.

Destroy target enchantment. If it's a Curse, you gain 3 life.

Exile target permanent. Smite the Unruly deals damage equal to that permanent's mana value to its controller and you gain that much life.

Target creature can't block this turn. Smokescreen deals 2 damage to that creature's controller.

Equipped creature gets +0/+2 and has menace.
Equip {1}

When Snarling Devil enters the battlefield, create four 1/1 black Possum Dog creature tokens.
At the beginning of each upkeep, put your choice of a +1/+1, lifelink, menace, trample, or vigilance counter on a token creature you control.

Scry 2 if a player lost life this turn. You draw two cards and you lose 2 life.

Exile the top card of each player's library. You may play one of those cards this turn.

Sneaking Capuchin can't be blocked except by creatures with defender.
{U}: Counter target spell or ability that targets Sneaking Capuchin.

Creatures with power less than Sneaking Peak's power can't block it.
At the beginning of your end step, if Sneaking Peak didn't attack this turn, put a +1/+1 counter on it.

Tap up to two target permanents. They don't untap during their controller's next untap step. You may put Snooze into its owner's library third from the top.

Snow Drift enters the battlefield tapped. When it does, 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, then you may mill that card.)
{T}: Add {U}.
{4}{U}: Snow Drift becomes an Elemental creature. (This effect lasts indefinitely.)

Enchant artifact or creature
Enchanted permanent doesn't untap during its controller's untap step.
Whenever you make first contact, scry 1.

Snowy Misthorn can block creatures with distorted as though it was tapped.

If you control seven or more creatures, you may cast Sociable Giant without paying its mana cost.
Trample

Target player mills six cards. Return each creature that shares a name with a card milled this way to its owner's hand.
Prophecy {1}{U} (Once each turn, you may exile a card with prophecy as you reveal it. When you do, you may cast it for its prophecy cost as long as it's exiled.)

Flying

Whenever you make first contact, return target creature card from your graveyard to the battlefield. (You make first contact the first time each turn you cast a spell with a name not in your graveyard or control already.)

Tap all lands target player controls and that player loses all unspent mana.

When Something in the Woods enters the battlefield or at the beginning of your upkeep, Something in the Woods explores. If it explores a creature card, you may have it become a copy of that card. (It loses this ability. To explore, 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, then you may mill that card.)

Enchant creature
Enchanted creature gets +1/+1 for each creature you control.

As Sorcerous Spyglass enters the battlefield, look at an opponent's hand, then choose any card name.
Activated abilities of sources with the chosen name can't be activated unless they're mana abilities.

When Sorrowslayer enters the battlefield, put a +1/+1 counter on target creature.
Remove a +1/+1 counter from Sorrowslayer: Trigger a death knell of a permanent you control. Activate only as a sorcery.