Altar Golem

Trample
Altar Golem's power and toughness are each equal to the number of creatures on the battlefield.
Altar Golem doesn't untap during your untap step.
Tap five untapped creatures you control: Untap Altar Golem.

Geist-Honored Monk

Vigilance
Geist-Honored Monk's power and toughness are each equal to the number of creatures you control.
When Geist-Honored Monk enters, create two 1/1 white Spirit creature tokens with flying.

Adeline, Resplendent Cathar

Vigilance
Adeline, Resplendent Cathar's power is equal to the number of creatures you control.
Whenever you attack, for each opponent, create a 1/1 white Human creature token that's tapped and attacking that player or a planeswalker they control.

Beast of Burden

Beast of Burden's power and toughness are each equal to the number of creatures on the battlefield.

Ria Ivor, Bane of Bladehold

Battle cry (Whenever this creature attacks, each other attacking creature gets +1/+0 until end of turn.)
At the beginning of combat on your turn, the next time target creature would deal combat damage to one or more players this combat, prevent that damage. If damage is prevented this way, create that many 1/1 colorless Phyrexian Mite artifact creature tokens with toxic 1 and "This creature can't block."

Silverwing Squadron

Flying, vigilance
Silverwing Squadron's power and toughness are each equal to the number of creatures you control.
Whenever Silverwing Squadron attacks, create a number of 2/2 white Knight creature tokens with vigilance equal to the number of opponents you have.

Angelic Exaltation

Whenever a creature you control attacks alone, it gets +X/+X until end of turn, where X is the number of creatures you control.

Sublime Archangel

Flying
Exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.)
Other creatures you control have exalted. (If a creature has multiple instances of exalted, each triggers separately.)

Seraph of the Masses

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Flying
Seraph of the Masses's power and toughness are each equal to the number of creatures you control.

Born to Drive

Enchant artifact or creature
As long as enchanted permanent is a creature, it gets +1/+1 for each creature and/or Vehicle you control.
Channel — {2}{W}, Discard Born to Drive: Create two 1/1 colorless Pilot creature tokens with "This creature crews Vehicles as though its power were 2 greater."

Hope Against Hope

Enchant creature
Enchanted creature gets +1/+1 for each creature you control.
As long as enchanted creature is a Human, it has first strike.

Crusader of Odric

Crusader of Odric's power and toughness are each equal to the number of creatures you control.