msem-instigator

When Serafina's Gift enters, if you cast it, target opponent gains control of it.
At the beginning of your upkeep, draw three cards, then discard two cards.

Deathtouch
When Nyx-Eater Basilisk enters, exile up to one target enchantment.
{2}{G}, Discard Nyx-Eater Basilisk: Exile target enchantment.

Double strike

Bestow {1}{G}{W}{U} (If you cast this card for its bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached to a creature.)
Krikam, the Wanderer and enchanted creature have protection from nonenchanted creatures.

Return target creature card from your graveyard to the battlefield. If you control a Demon, each opponent loses 3 life.

Harmony — Exciting Band deals 3 damage to any target.
When Exciting Band enters, harmonize. (Trigger up to one harmony of one permanent you control.)

{1}{W}: Exile Furtive Witch. If you do, exile another target nonland permanent. Return both of those cards to the battlefield at the beginning of the next end step under their owners' control.

Flying
Cruel Fledgling enters with a +1/+1 counter on it if six or more cards are in your graveyard.

{1}{G}{G}, Discard a card: Destroy target artifact or enchantment.
At the beginning of your end step, if twelve or more cards are in your graveyard, create two 3/3 green Beast creature tokens.

Whenever Leija, the Bloodied Queen attacks, you may pay {R}{R}{R}{R}. If you do, it deals 4 damage to each other creature, each player, and each planeswalker.

Whenever Yrodu, the Lotus Ablaze attacks, eight target permanents don't untap during their controller's next untap step.
Whenever Yrodu blocks a creature, destroy that creature at end of combat.

Target creature gets -4/-4 until end of turn. When it dies this turn, create two 1/1 black Worm creature tokens.

Flash
Enchant creature
Enchanted creature gets +2/+2 and can't be blocked by creatures with power 2 or less.

Target creature you control gets +1/+1 and gains hexproof until end of turn.

Equipped creature gets +1/+1.
Whenever equipped creature attacks, create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)
Equip {2}

Whenever a creature you control deals combat damage to a player, put a tally counter on this enchantment. If it was a Dwarf or Elf, put two on it instead.
Remove two tally counters from this enchantment: Draw a card.

Trample
Whenever Charging Cassowary deals combat damage to a player, you may cast a copy of an Adventure of a permanent you control.

Hidden Prowess deals 2 damage to target creature. When that creature dies this turn, create a 1/1 red Elemental creature token.

Concord — Whenever Bubbledome Captain attacks, if there are four or more card types among permanents you control, each other attacking creature gets +1/+1 until end of turn.

First strike
If one or more creature tokens would be created under your control, for each of those tokens, you may create three 2/2 green Cat Warrior creature tokens instead.

Whenever you cast an artifact or enchantment spell, scry 1, then create a 1/1 white Merfolk creature token.
Whenever you cast a Merfolk spell, look at the top card of your library. If it's an artifact or enchantment card, you may reveal it and put it into your hand.

Each player chooses up to one permanent they control of each permanent type, then sacrifices the rest. (The permanent types are artifact, creature, enchantment, land, and planeswalker.)

{T}: Add {G}. Spend this mana only to cast a creature spell or activate an ability of a creature.
At the beginning of combat on your turn, if you control a creature with power 4 or greater, Vassal of the Wild gets +2/+1 and gains vigilance until end of turn.

When Powercell Engineer enters, create a tapped colorless Powercell artifact token with “{T}: Add {C}.”

Deathtouch