msem-instigator

Rhapsody {3}{W}{W} (Pay {3}{W}{W} to cast this as a 4/4, or as a sorcery to make it become a 4/4.)
Lifelink

Whenever Aspiring Hero attacks alone, put a +1/+1 counter on it.
When Aspiring Hero dies, each opponent gains life equal to its power.

Vanguard — Whenever a creature you control attacks alone, it gets +1/+1 until end of turn.

Target player sacrifices an attacking creature.
Bulwark — That player sacrifices two attacking creatures instead if you control a creature with toughness 4 or greater.

Creatures you control get +2/+0 until end of turn. Untap each Army you control.

Exile target nonland permanent. For each of its colors, its controller creates a 1/1 colorless Spirit creature token.

First strike
Chronicle (As this enters and after your draw step, add a lore counter. Stop after III.)
[Lore I-II] Put a +1/+1 counter on each of up to two other target creatures you control.
[Lore III] Remove all lore counters from Astral Capricine. Create two 0/1 white Goat creature tokens.

Once each turn, when Atal, the Shroudmaker enters or you attack with one or more Horrors, you may create two tapped 1/1 colorless Human creature tokens. If Atal isn't a token, creatures you control gain flying until end of turn.
{2}{W}{W}, Discard Atal: Create a token that's a copy of Atal, the Shroudmaker, except it's 4/4 and isn't legendary. Activate only as a sorcery.

Flying
When Atieh's Elite enters, judge another target creature you control. (Honor it by putting a +1/+1 counter on it or condemn it by sacrificing it to draw a card.)
Whenever you honor a creature, until end of turn, that creature has base power and toughness 4/4, gains flying, and becomes an Angel in addition to its other types.

Choose one or both —
• Prevent all combat damage that would be dealt to creatures this turn.
• Detain target creature. (Until your next turn, that creature can't attack or block and its activated abilities can't be activated.)

First strike (This creature deals combat damage before creatures without first strike.)
When Attended Knight enters, create a 1/1 white Soldier creature token.

Enchant creature
As long as you control an untapped creature, enchanted creature can't attack or block.

{2}{W}: Audacious Knight gains first strike and vigilance until end of turn. (It deals combat damage before creatures without first strike. Attacking does not cause it to tap.)

Enchant creature
When Aura of Leadership enters, create four 1/1 white Human Soldier creature tokens.
Enchanted creature gets +2/+2.

When Auramancer enters, you may return target enchantment card from your graveyard to your hand.

Target player sacrifices an enchantment.
Spell mastery — If there are two or more instant and/or sorcery cards in your graveyard, return up to one enchantment card from your graveyard to your hand.

Exile target tapped creature. Its controller gains 3 life.

Choose target creature or planeswalker. Its controller may exile it. If that player doesn't, they sacrifice all other creatures and planeswalkers they control.

Choose one —
• You gain hexproof until end of turn.
• Target creature you control gains double strike until end of turn.
• Exile target card from a graveyard. You gain 4 life.

Lifelink

At the beginning of your end step, if you control two or more artifacts and/or enchantments, transform Avacyn's Partisan.

Flying, vigilance
At the beginning of your end step, return up to one target permanent card from your graveyard to the battlefield with an indestructible counter on it.

Vigilance
Avatar of Utsenchep can block any number of creatures.
All creatures able to block Avatar of Utsenchep do so.

When Avaz Banner enters, attach it to target creature you control.
Equipped creature gets +2/+2 and is a Soldier Army in addition to its other types.
Equip {3}

(As an Encounter enters, choose an opponent to protect it. You and others can attack it. When defense counters are removed, create a 0/0 Army token if you don't control one, then put that many +1/+1 counters on a Army you control.)
When Avaz Rising enters, return target creature card from your graveyard to the battlefield. That creature becomes an Army in addition to its other types.