msem-instigator

When Pensive Muse enters, create a white Aura enchantment token named Seal's Love attached to target creature you control. The token has enchant creature and “Enchanted creatures you control get +1/+1.”

Whenever a creature attacks you or a planeswalker you control, Pitfall Pangolin gets +1/+0 until end of turn.

Flying
When Planchette Poltergeist enters, you may exile target creature. Its owner may cast it from exile for as long as it remains exiled.

Flying
Whenever Pledged Griffin attacks, another target attacking creature gains flying until end of turn.

Protector of the Gates can't attack unless it's equipped, enchanted, or has a card inscribed onto it.

{G}: Exile target card from a graveyard. You gain 1 life and Purging Watchkeeper gets +1/+1 until end of turn.

When Rabudan Chiseler enters, you may search your library for an Aura or Equipment card, reveal it, put it into your hand, then shuffle.

When Roving Chaplains enters, create two 1/1 white Spirit creature tokens with flying.
{W}, Tap another untapped creature you control: Tap target nonland permanent an opponent controls.

First strike
Prevent all noncombat damage that would be dealt to Royal Knight.

When Ruler of Cities enters, you may search your library for an Aura that could enchant a land you control, reveal it, put it into your hand, then shuffle.
Whenever an Aura becomes attached to a land you control, you gain 2 life.

When Safety Expert enters, if you have more life than your starting life total, put a +1/+1 counter on target creature.

When Sandbluff Confiscator enters, you may tap or untap target artifact or creature.

Flash
Flying
When Sandstreamer enters, target permanent gains indestructible until end of turn.

First strike
Whenever Scion of the Pack enters or one or more creatures you control deal combat damage to an opponent or planeswalker, create a 2/2 green Hound creature token.

Augmented — At the beginning of combat on your turn, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, put a +1/+1 counter on Second Wave Explorer.

As long as a creature you control has flying, creatures you control have flying. The same is true for first strike, double strike, deathtouch, haste, hexproof, indestructible, lifelink, menace, reach, trample, and vigilance.

Spirited (When this creature enters, you may activate one of its activated abilities without paying its cost.)
{2}{W}: Create a 1/1 white Human Samurai creature token.

Whenever an enchantment you control enters, you may gain 2 life.
Whenever you gain life, reveal the top card of your library. If it's an enchantment card, put it into your hand.

Spirited (When this creature enters, you may activate one of its activated abilities without paying its cost.)
{2}{W}: Target creature gains vigilance until end of turn.

Vigilance
Melee (Whenever this creature attacks, it gets +1/+1 until end of turn for each opponent you attacked this combat.)
Whenever Silvercrest Sentry attacks, untap up to one target legendary creature you control.

Whenever another creature with mana value 2 or less you control enters, tap target creature an opponent controls.

Flying
Melee (Whenever this creature attacks, it gets +1/+1 until end of turn for each opponent you attacked this combat.)
Your opponents can't cast spells during combat and can't activate abilities during combat unless they're mana abilities.

Resolute — At the beginning of combat on your turn, if Skyward Gaveller's power is greater than its base power, it gains flying until end of turn.

Flying, vigilance

Whenever Soli Arbalist or a nontoken Angel or Nephilim you control enters, amass Soldiers 2. If it was an Angel, amass Soldiers 4 instead. (To amass Soldiers {2}, put two +1/+1 counters on an Army you control. It's also a Soldier. If you don't control one, create a 0/0 black Soldier Army creature token first.)