msem-instigator

Flying (This creature can't be blocked except by creatures with flying or reach.)
When Trained Warhawk enters, create a 1/1 white Soldier creature token.

Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Until end of turn, target creature gets +1/+1 and gains lifelink.

Whenever a creature you control enters, if you didn't cast it from your hand, put a +1/+1 counter on it.
{3}{W}: Exile target creature you control, then return it to the battlefield under its owner's control.

Instant and sorcery spells your opponents cast cost {1} more to cast.

Whenever another creature enters, you gain 1 life.

When Seluriel's Blessing enters, put a +1/+1 counter on each creature you control.
Creatures you control enter with an additional +1/+1 counter on them.
Creatures you control with counters on them have vigilance and indestructible.

[+1]: You gain 1 life. Put a +1/+1 counter on up to one target creature.
[–3]: Exile target creature. Its controller gains life equal to its power.
[–8]: You get an emblem with “Creatures you control get +1/+1 and have double strike and lifelink.”

Flying
Whenever another creature you control attacks, you may pay {1}. If you do, put a +1/+1 counter on it.

When Mass Orator enters, if it isn't a token, populate. (Create a token that's a copy of a creature token you control.)
Creature tokens you control get +1/+1.

Whenever you gain life, you may pay {X}, where X is less than or equal to the amount of life you gained. If you do, draw X cards.

Prevent all damage that would be dealt to you this turn. You gain 1 life for each creature you control.

When Knight's Attendant enters, create a 2/2 white Knight creature token with vigilance.

Enchant creature
When Knightly Valor enters, create a 2/2 white Knight creature token with vigilance. (Attacking doesn't cause it to tap.)
Enchanted creature gets +2/+2 and has vigilance.

Create a 2/2 white Knight creature token with vigilance, then populate. (Create a token that's a copy of a creature token you control.)

Creatures you control get +1/+1 until end of turn. Token creatures you control get an additional +1/+1 until end of turn.

Flying (This creature can't be blocked except by creatures with flying or reach.)
Heavensent Emissary enters with a +1/+1 counter on it for each other creature with flying you control.

Vigilance
{W}: Heaven's Champion gains first strike until end of turn.

Flying, lifelink

Populate, then you gain 2 life. (Create a token that's a copy of a creature token you control.)

Whenever another creature you control enters, Flightpath Trainee gains flying until end of turn.

Fellor Vanguard gets +1/+1 as long as you control a Mountain.
{1}{R}: Fellor Vanguard gets +1/+0 until end of turn.

Destroy all nontoken creatures.

Whenever you gain life, put a +1/+1 counter on Faithful Acolyte.
Faithful Acolyte has lifelink as long as it has four or more +1/+1 counters on it.