TEXT: A MUSICAL SUBCLASS FOR FIGHTERS
  BY KAI LINDER
  
  INTRODUCTION
  Horncallers are a well-known staple of heroic tales, the
  charismatic fighters that lead armies to victory on the
  battlefield. They use their warhorns to issue commands
  over great distances, influencing the tides of battle and
  enabling many to act as one. They are the the sonorous
  voice of leadership, and some use this power to ever
  greater and more magical effect, becoming adventurers
  of legend capable of pushing allies beyond their limits.
  DISTANT CALL
  At 3rd level, you’ve been trained to use the horn as a
  method of communication. You gain proficiency with
  the horn.
  As an action, you can use your horn to communicate
  short messages of five words or less audible up to 1
  mile away. The meaning of your call is understood by
  everyone who hears it, unless you have previously
  established a specific signal or system with a desired
  recipient.
  ANNOUNCE ORDERS
  Also at 3rd level, you are able to issue battlefield orders
  to your allies. You can blow your horn as a bonus
  action to announce an order of your choice from the
  Order Options detailed below. Friendly creatures
  within 100 feet of you that hear your horn can perform
  the announced order.
  Order Options.
  Advance. A creature can use its reaction to move up
  to 10 feet.
  Charge. A creature can use its reaction to move up to
  15 feet towards a hostile creature it can see.
  Fall Back. A creature can use its reaction to move 5
  feet without provoking opportunity attacks.
  Focus Fire. You mark a creature you can see within
  100 feet until the start of your next turn. Whenever an
  ally deals damage to a marked creature, it takes
  additional damage of that type equal to your Charisma
  modifier.
  Rally Point. You mark a location or space you can see
  within 100 feet of you for the next minute. While
  moving towards that location or space, friendly
  creatures are unaffected by difficult terrain and ignore
  effects that would reduce their speed.
  Take Cover. A creature can use its reaction to gain
  half cover until the end of its next turn or it moves at
  least 5 feet.
  You can announce an order a number of times equal
  to your Charisma modifier (minimum once), and
  regain all expended uses when you finish a short or
  long rest.
  RALLYING HORN
  At 7th level, you can push your allies’ stamina onwards.
  When you use your Second Wind feature, friendly
  creatures within 100 feet of you each regain hit points
  equal to half your fighter level.
  SIGNAL OF DEFIANCE
  When you reach 10th level, your resistance is an
  example to your allies. Immediately after you succeed
  on a saving throw, you can use your reaction to issue a
  defiant call on your horn. Each friendly creature within
  100 feet of you that hears the horn can add your
  Charisma modifier to one ability check, attack roll, or
  saving throw they make in the next minute.
  HOLD THE LINE
  At 15th level, you can create a barrier of vibrating
  sound. You can use an action to cast wall of force,
  requiring no components. When you cast the spell, you
  can choose a number of creatures up to your Charisma
  modifier to ignore the effects of the spell.
  Once you have used this feature, you can’t do so
  again until you finish a long rest.
  WARRIOR’S SHOCKWAVE
  At 18th level you can summon a rush of heroic spirits.
  You blow your horn as an action, creating a shockwave
  of sound in the form of charging ethereal warriors that
  ripples outward from you. Each creature you choose
  within 50 feet of you must succeed on a Strength
  saving throw or take 10d10 thunder damage, and be
  pushed 15 feet away from you and knocked prone. A
  creature that succeeds on its saving throw takes half as
  much damage, is pushed 5 feet away from you, and isn’t
  knocked prone.
  Once you have used this feature, you can’t do so
  again until you finish a long rest.
  FIGHTER MARTIAL ARCHETYPE: THE HORNCALLER
  
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  material is used with permission under the Community Content Agreement for Dungeon Masters Guild. All other original material in this work is copyright 2020 by Kai Linder and published
  under the Community Content Agreement for Dungeon Masters Guild.
  MAGIC ITEMS
  HORNED CROWN
  Wondrous item, uncommon
  This metal crown has 10 sharp obsidian horns
  attatched to it. While wearing the crown, it can be used
  to make headbutting weapon attacks, and counts as a
  martial melee weapon that deals 1d8 piercing damage +
  your Strength modifier.
  Additionally, you can use an action to rip off one of
  the horns and throw it at a space you can see within 30
  feet of you to summon a hail of arrows. Each creature
  within 15 feet of the target space must make a DC14
  Dexterity saving throw. A creature takes 2d10 piercing
  damage on a failed save, or half as much on a successful
  one.
  When no more horns remain, the crown breaks.
  DRAGONCALLER HORN
  Wondrous item, very rare (requires attunement)
  This immense curved horn is made from the horn of
  an ancient gold dragon, and has been engraved with
  rings of arcane runes.
  While attuned to the horn, you can speak draconic
  and have advantage on Charisma checks made to
  influence dragons.
  You can use an action and blow the horn to send a
  telepathic summons to the nearest dragon within 30
  miles. The dragon is magically compelled to come to
  the location at which you blew the horn. Once you
  have summoned a dragon in this way, you can’t do so
  again until you finish a long rest.
  FORLORN HORN
  Wondrous item, common
  The forlorn horn is a tiny floppy grey horn You can use
  an action to play the horn, causing it to make a sad
  horn sound. Each creature within 30 feet must succeed
  on a DC 12 Wisdom saving throw or feel sad and
  lonely for the next 10 minutes.
  Each time you use the forlorn horn, roll a d4. On a
  result of 1 the horn backfires and targets only you.
  HORN OF CONJURATION
  Wondrous item, varies (requires attunement by a creature
  proficient with horns)
  A horn of conjuring is a powerful magical horn, superior
  to an ordinary horn in every way. Seven types of these
  instruments exist, each named after their most famous
  wielder. The following table lists the spells common to
  all horns, as well as the spells specific to each one and
  its rarity.
  A creature that attempts to play the horn without
  being attuned to it must succeed on a DC 15 Wisdom
  saving throw or take 2d4 psychic damage.
  The horn can be used as a spellcasting focus. You can
  use an action to play the horn and cast one of its spells.
  Once the horn has been used to cast a spell, it can’t be
  used to cast that spell again until the next dawn. The
  spells use your spellcasting ability and spell save DC.
  You can play the horn while casting a spell that
  causes any of its targets to be deafened on a failed
  saving throw, thereby imposing disadvantage on the
  save. This effect applies only if the spell has a somatic
  or a material component.
  CREDITS
  Design: Kai Linder (Twitter: @Paradoliak)
  Cover Art: Kredinca (Twitter: @Lost_Krendel)
  Cover Layout: Bethany Bracken
  (Twitter: @BethanyDnD)
  Interior Art: Shutterstock
  Horn
  Rarity
  Spells
  All
  -
  find steed, sending, thunderwave, plus
  the spells listed for the par�cular horn
  Abdo’s
  wazza
  uncommon animal messenger, summon beast,
  summon fey
  Abhishek’s
  tutari
  rare
  dust devil, grasping vine, summon
  elemental
  Gregg’s
  bugle
  uncommon conjure food and water (sausage rolls
  and tea only), summon shadowspawn
  Hani’s shofar rare
  heat metal, sha�er, summon construct
  Maja’s lur
  very rare
  insect plague, summon fiend, summon
  lesser demon
  Morgwaeth’s
  carnyx
  rare
  dissonant whispers, hunger of Hadar,
  summon aberra�on
  Rowan’s
  shawm
  rare
  Mordenkainen’s faithful hound, spirit
  guardians, summon celes�al
  The adventurers crashed into the front line of hobgoblins,
  slinging spell and blade. A clarion call filled the air and as one
  the hobgoblin host drew back and locked shields. A lone hobgoblin
  stood atop a hill 100 feet back, silhouetted against the setting sun,
  banner flapping in the wind. They raised their warhorn and
  gave three short blasts, and a volley of arrows launched through
  the air directly towards the the cleric. The cleric gripped his skull
  amulet tight and began to flee just as yet another horn blast
  rolled across the field, this time with a strange depth that made
  the air shudder. *SMACK* The cleric slammed into an invisible
  force. His escape was cut off by some magical force. He
  desparately patted for a gap as the arrows fell.
  SOUNDS OF THE HORNCALLER
  Horns are among the earliest known instruments, and
  their communication and military uses are well known,
  from goatherd to folkhero to religious ceremony. Here are
  a few examples of horns in use:
  Celtic Carnyx: https://www.youtube.com/watch?v=EOR7VKcSb9k
  Shofar prayer: https://www.youtube.com/watch?v=Rnkb7M3dKTg
  Tutari playing: https://www.youtube.com/watch?v=GTjkJLcDXYw
  
SOURCE: textdata/thevault/Dungeons & Dragons [multi]/Suppliment/A Musical Subclass for Fighters - The Horncaller.pdf