msem-instigator

When Rethia Cultivator enters, you may search your library for a land card, reveal it, put it into your hand, then shuffle.

Flash
When Ambush Gharial enters, it fights up to one target creature. If that creature would die this turn, exile it instead.

Bloodprice {2}{B} (You may cast this card by sacrificing a creature and paying its bloodprice.)
Create X 2/2 black Demon creature tokens, where X is one plus the number of creatures that died this turn.

Transcend (Activate as a sorcery to gain the next type and a +1/+1 counter.)
When Dai Gui enters, create a 1/1 green and blue Bird creature token with flying and “{T}: Add one mana of any color.”
{X}{X}{G}{U}: Demigod — You gain X life and you draw X cards. X can't be 0.
{X}{X}{G}{U}: God — Put up to X creature cards from your hand onto the battlefield.

Whenever Almgrove Spellblade attacks, harmonize. (Trigger up to one harmony of a permanent you control.)
Harmony — Exile the top two cards of your library. Until end of turn, you may play cards exiled by Almgrove Spellblade.

When Bjarndyr Outfitter enters, arm up to two target creatures you control. (Create a colorless Equipment artifact token with “Equipped creature gets +1/+0” and equip {2}, then attach it to that creature.)

Rosegill Rover can't be blocked.
Whenever Rosegill Rover attacks, you may discard a card. If you do, draw a card.

Your opponents can't gain life.
If a source you control would deal damage to an opponent, it deals that much damage plus 1 instead.
{3}{R}: Transform Pyromantic Duo. Activate only if it's attacking.

Enchant creature
When Child of the Pack enters, create a 2/2 green Wolf creature token.
Enchanted creature gets +1/+1 for each Wolf you control.

Adorned — Daelish Hopeful has first strike as long as it's equipped and/or enchanted.

When Phantasmal Samaritan enters, you gain 4 life.

Menace

Flash
When Witch of the Veil enters, if it was cast, you may sacrifice a creature. If you do, return that card to the battlefield under its owner's control.

Spirited (When this creature enters, you may activate one of its activated abilities without paying its cost.)
{4}{G}: Target creature gets +2/+2 until end of turn.

Flying, deathtouch, lifelink
Ride {1}{B} ({1}{B}: Transform this and attach it to target creature you control without a Steed. Ride only as a sorcery.)
You may activate Bonescourge Kazadrak's ride ability from your graveyard by sacrificing a creature in addition to paying its other costs.

When Runebreaker Mage enters, return another target nonland permanent you control and target nonland permanent you don't control to their owner's hands.

When Reverence Seeker dies, you may return another target Knight card from your graveyard to your hand.

Enchant creature
{U}: Tap enchanted creature.
{1}{U}: Untap enchanted creature and gain control of it until end of turn.

{1}, {T}: Put a +1/+1 counter on Jade Sentinel. Activate only if you control a creature with power greater than Jade Sentinel's.

As long as you control exactly one creature, no more than one creature can attack or block each combat.

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.

Escalate {B} (Pay this cost for each mode chosen beyond the first.)
Choose one or both —
• Put target permanent on top of its owner's library.
• For each library, look at the top three cards of that library, put any number of them into their owner's graveyard, then the rest back on top in any order.

When Life from Death enters, create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)
Whenever a nontoken creature you control dies, create a 1/1 green Saproling creature token.