msem-instigator

Search your library and/or graveyard for a creature card with mana value X or less and put it onto the battlefield with an additional -1/-1 counter on it. If you search your library this way, shuffle.

When Twisted Predator dies, you draw a card and you lose 1 life.

Equipped creature gets +2/+2.
Whenever equipped creature attacks, creature spells you cast cost {2} less to cast this turn.
Equip {2}

When Ulek Elder enters, look at the top card of your library. You may put it into your graveyard.

When Ulvenwald Ranger enters, surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)
{1}{G}: Transform Ulvenwald Ranger. Activate only if it's attacking.

If a creature card would be put into an opponent's graveyard from anywhere, instead exile it, then copy it. You may cast the copy. (You still pay its costs, including color. Copies of permanents enter as tokens.)

Flash
If a card or token would be put into an opponent's graveyard from anywhere, exile it instead.

Unassuming Waif can't be blocked.
Unassuming Waif gets +1/+0 for each other Warrior you control.

Choose one —
• Counter target spell unless its controller pays {2}.
• Tap target creature. It doesn't untap during its controller's next untap step.

You may pay {W} and tap an untapped Monk you control rather than pay this spell's mana cost.
The next 3 damage that would be dealt to you and/or permanents you control this turn is dealt to any target instead.

Enchant creature
Enchanted creature can't be blocked.
{1}{G}: Enchanted creature gets +1/+1 and gains hexproof until end of turn.

When Unbound Expanse enters, if an opponent controls more lands than you, create a Plains token. (It's a basic land with “{T}: Add {W}.”)
{3}{W}, Sacrifice Unbound Expanse: Exile each nonland permanent you control, then return those cards to the battlefield under your control. Activate only as a sorcery.

Escalate—Return another spell you control to its owner's hand. (Pay this cost for each mode chosen beyond the first.)
Choose one or both —
• Draw a card.
• Draw a card.

Target creature gets +1/+0 and gains indestructible until end of turn. Draw a card if you control an Angel, Demon, Faerie or Spirit.

Whenever Unbudging Badger attacks, if its power is 4 or greater, it gains trample until end of turn.

Search your library for a permanent card with mana value X or less, reveal it, put it into your hand, then shuffle.

Look at the top two cards of your library. Put one of them into your hand, then you may have any number of players each mill three cards.

Target creature gets -X/-X until end of turn, where X is 2 plus the number of cards named Undead Servant in your graveyard.
As long as this card is in your graveyard, its name is Undead Servant.

Enchant land you control
Whenever enchanted land is tapped for mana, it produces an additional mana of that type.
{1}{G}, Sacrifice Under Untamed Skies: Destroy target creature with flying.

{T}, Sacrifice a permanent: Investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

Undercroft Portal enters with four barrier counters on it.
Invocation — Whenever you spend four or more mana to cast a spell or activate an ability during your turn, draw a card and remove a barrier counter from Undercroft Portal. Then if it has no barrier counters
on it, transform it.

Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)

Up to one target creature gets -2/-2 until end of turn. Put a +1/+1 counter on up to one target creature you control.

When Undermarket Favors enters, target player discards a card, then mills four cards.
{1}, Sacrifice Undermarket Favors: Draw a card.

Vigilance
Whenever Underpass Sentinel enters or attacks, you may put a +1/+1 counter on another target creature you control without one.
Sacrifice Underpass Sentinel: Embattled creatures you control gain hexproof and indestructible until end of turn. (A creature is embattled if it has a counter on it or a permanent you control attached to it.)