Herald of Leshrac

Flying
Cumulative upkeep—Gain control of a land you don't control. (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
Herald of Leshrac gets +1/+1 for each land you control but don't own.
When Herald of Leshrac leaves the battlefield, each player gains control of each land they own that you control.

Centaur's Herald

{2}{G}, Sacrifice Centaur's Herald: Create a 3/3 green Centaur creature token.

Brass Herald

As Brass Herald enters the battlefield, choose a creature type.
When Brass Herald enters the battlefield, reveal the top four cards of your library. Put all creature cards of the chosen type revealed this way into your hand and the rest on the bottom of your library in any order.
Creatures of the chosen type get +1/+1.

Azorius Herald

Azorius Herald can't be blocked.
When Azorius Herald enters the battlefield, you gain 4 life.
When Azorius Herald enters the battlefield, sacrifice it unless {U} was spent to cast it.

Herald of Faith

Flying
Whenever Herald of Faith attacks, you gain 2 life.

Herald of the Pantheon

Enchantment spells you cast cost {1} less to cast.
Whenever you cast an enchantment spell, you gain 1 life.

Herald of Torment

Bestow {3}{B}{B} (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.)
Flying
At the beginning of your upkeep, you lose 1 life.
Enchanted creature gets +3/+3 and has flying.

Wirewood Herald

When Wirewood Herald dies, you may search your library for an Elf card, reveal that card, put it into your hand, then shuffle.

Herald of the Host

Flying, vigilance
Myriad (Whenever this creature attacks, for each opponent other than defending player, you may create a token that's a copy of this creature that's tapped and attacking that player or a planeswalker they control. Exile the tokens at end of combat.)

Yeva, Nature's Herald

Flash (You may cast this spell any time you could cast an instant.)
You may cast green creature spells as though they had flash.

Sphinx's Herald

{2}{U}, {T}, Sacrifice a white creature, a blue creature, and a black creature: Search your library for a card named Sphinx Sovereign, put it onto the battlefield, then shuffle.

Behemoth's Herald

{2}{G}, {T}, Sacrifice a red creature, a green creature, and a white creature: Search your library for a card named Godsire, put it onto the battlefield, then shuffle.

Herald of the Fair

When Herald of the Fair enters the battlefield, target creature you control gets +1/+1 until end of turn.

Dragon's Herald

{2}{R}, {T}, Sacrifice a black creature, a red creature, and a green creature: Search your library for a card named Hellkite Overlord, put it onto the battlefield, then shuffle.

Herald of Kozilek

Devoid (This card has no color.)
Colorless spells you cast cost {1} less to cast.

Demon's Herald

{2}{B}, {T}, Sacrifice a blue creature, a black creature, and a red creature: Search your library for a card named Prince of Thralls, put it onto the battlefield, then shuffle.

River Heralds' Boon

Put a +1/+1 counter on target creature and a +1/+1 counter on up to one target Merfolk.

Angel's Herald

{2}{W}, {T}, Sacrifice a green creature, a white creature, and a blue creature: Search your library for a card named Empyrial Archangel, put it onto the battlefield, then shuffle.

Benalish Heralds

Herald of Dromoka

Vigilance
Other Warrior creatures you control have vigilance.

Herald of Anguish

Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for {1}.)
Flying
At the beginning of your end step, each opponent discards a card.
{1}{B}, Sacrifice an artifact: Target creature gets -2/-2 until end of turn.

Herald of the Sun

Flying
{3}{W}: Put a +1/+1 counter on another target creature with flying.

Nebelgast Herald

Flash (You may cast this spell any time you could cast an instant.)
Flying
Whenever Nebelgast Herald or another Spirit enters the battlefield under your control, tap target creature an opponent controls.

Herald of the Dreadhorde

When Herald of the Dreadhorde dies, amass Zombies 2. (Put two +1/+1 counters on an Army you control. It's also a Zombie. If you don't control an Army, create a 0/0 black Zombie Army creature token first.)

Herald of Anafenza

Outlast {2}{W} ({2}{W}, {T}: Put a +1/+1 counter on this creature. Outlast only as a sorcery.)
Whenever you activate Herald of Anafenza's outlast ability, create a 1/1 white Warrior creature token.

Victory's Herald

Flying
Whenever Victory's Herald attacks, attacking creatures gain flying and lifelink until end of turn.

Herald of Secret Streams

Creatures you control with +1/+1 counters on them can't be blocked.

Herald of Serra

Flying, vigilance
Echo {2}{W}{W} (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)

Herald's Horn

As Herald's Horn enters the battlefield, choose a creature type.
Creature spells you cast of the chosen type cost {1} less to cast.
At the beginning of your upkeep, look at the top card of your library. If it's a creature card of the chosen type, you may reveal it and put it into your hand.

Herald of War

Flying
Whenever Herald of War attacks, put a +1/+1 counter on it.
Angel spells and Human spells you cast cost {1} less to cast for each +1/+1 counter on Herald of War.