Onmyoji

In the Emerald Kingdoms, the Onmyoji were the specialized spellcasters who were seen as a sort of vizier, holy man, and ritual-keepers for the Shogunate dynasties. Renowned for their sage wisdom and vast intellects, they are the "court magicians" of the clans, and while not particularly numerous compared to the Shugenja or other more sorcerous spellcasters, the influence and knowledge of the Onmyoji is undoubted, and having a person chosen to learn these disciplined teachings is supposedly a high honor for any merchant or noble family.

The Onmyoji is a specialist spellcaster who utilizes arcane foci of various different sorts in order to bestow special effects into their spellcasting. These unique wizards are the specialist class that serves the Emerald Courts in matters of advice, divination, enchantments, and magical protections, among many other services. These spellcasters suffer directly from a lack of any specialization, except perhaps that their usage of arcane foci is a specialization unto itself that indeed provides them with greater ability to cast through those. However, all Onmyoji rely on foci and rituals, and indeed they may actually find some, more spontaneous forms of spellcasting difficult without those tools, unlike other Wizards. 

Apart from this drawback, the Onmyoji utilize four very unique types of arcane focus that are special for what can be done with them. These are the Astonomical Chart, Divining Bones,  Kami Statue, and Mahoutsukai Weapon. These must be made in very exacting methods, with very specific techniques. A crafter proficient in Calligrapher's Tools or Woodcutter's Tools can craft and repair an Astronomical Chart. A crafter proficient with Leatherworker's Tools or Survival can craft and repair Divining Bones, A crafter proficient in Gemcutter's Tools or Sculptor's Tools can craft and repair a Kami Statue, and a crafter proficient with Smith's Tools or Tinkerer's Tools can craft and repair a Mahoutsukai Weapon.

Onmyoji Foci

2nd level Onmyoji class feature

The Onmyoji utilize such powerful Arcane Foci with such extraordinary familiarity, that they unlock unique capabilities with spells they cast through those foci:

Astronomical Chart: These special star charts are etched or block-printed onto wooden squares about an inch wide and display the positions of certain stars and constellations. Whenever you cast a Divination or Enchantment spell or a spell that enables teleportation and you are using an Astronomical Chart as an arcane focus, you may cast Divination and Enchantment spells with duration longer than instant with 3 extra rounds of duration, and additionally, if you cast a spell that enables teleportation, you may add 10 feet to the distance allowed by that teleportation.

Divination Bones: These are a set of animal bones, some short and some long, etched with arcane symbols. Whenever you cast a Divination or Necromancy spell using Divining Bones as an arcane focus, you may cast those spells without material and verbal components, and if those spells have a spell save DC, you increase that DC by 1 for all targets of that spell. Also, whenever you cast a spell that bestows temporary hit points using Divination bones as a focus, you may add your Intelligence modifier to the number of hit points bestowed by the spell.

Kami Statue: This is a small statuette, crafted from clay, ebony, ivory, or gemstone made in the image of a kami spirit. Whenever you cast an Abjuration or Transmutation spell, you may cast that spell with one additional target within that spell's range, even if that spell has only one target or if the spell has a range of self. If the spell has a touch range or a range of self, any creature within 5 feet of you may become the target if you have already targeted yourself. Casting a spell in this way always uses at least an action to cast it, even if the casting time is shorter.

Mahoutsukai Weapon: A specially prepared and ornately decorated weapon. The Onmyoji tend to select ritually prepared weapons such as a Wakizashi dagger, or a Shakujo quarterstaff. Whenever you cast a Conjuration or Evocation spell or a spell that requires a spell attack roll using your Mahoutsukai Weapon as an arcane focus, you may choose to either treat all 1's rolled on damage dice as if they were 2's, or alternately, you may choose to gain a +2 bonus on the melee spell attack roll for that spell. Additionally, Mahoutsukai Weapons are made to be combat ready at any time, and are considered magic weapons for purposes of damage resistance.

Because the Onmyoji are so reliant on their foci, if you cast a spell using one of your Onmyoji Foci and gain a benefit from this feature, those proficient in arcana who would attempt to identify the school of the spell you are casting have advantage on such rolls or checks.

Astronomical Chart

Whenever you cast a Divination or Enchantment spell or a spell that enables teleportation and you are using an Astronomical Chart as an arcane focus, you may cast Divination and Enchantment spells with duration longer than instant with 3 extra rounds of duration, and additionally, if you cast a spell that enables teleportation, you may add 10 feet to the distance allowed by that teleportation.

Divination Bones

Whenever you cast a Divination or Necromancy spell or a spell that bestows temporary hit points using Divining Bones as an arcane focus, you may cast those spells without material and verbal components, and if those spells have a spell save DC, you increase that DC by 1 for all targets of that spell; additionally, whenever you cast a spell that bestows temporary hit points, you may add your Intelligence modifier to the number of hit points bestowed by the spell.

Kami Statue

Whenever you cast an Abjuration or Transmutation spell, you may cast that spell with one additional target within that spell's range, even if that spell has only one target or if the spell has a range of self. If the spell has a touch range or a range of self, any creature within 5 feet of you may become the target. Casting a spell in this way always uses at least an action, even if the casting time is less.

Mahoutsukai Weapon

Whenever you cast a Conjuration or Evocation spell or a spell that requires a spell attack roll using your Mahoutsukai Weapon as an arcane focus, you may choose to either treat all 1's rolled on damage dice as if they were 2's, or alternately, you may choose to gain a +2 bonus on the melee spell attack roll for that spell. Additionally, Mahoutsukai Weapons are combat ready at any time, and are considered magic weapons. 

Beads of the Many-handed God

6th level Onmyoji class feature

Your dedication to using foci has taught you to craft and use a very unique and special wondrous magic item that all Onmyoji utilize known as the Beads of the Many-handed God. This extraordinary bracelet has the following properties:

Beads of the Many-Handed God

You can wear these beads while casting spells and use them as an arcane focus for those spells. When you cast a Conjuration spell using the Beads of the Many-handed God as an arcane focus, you have advantage on Constitution saving throws to maintain concentration on such spells.

Creating one of these items takes a special ritual that the Onmyoji knows, in which they use 200 gold pieces of special powders, incense, and beads, and two hours of ritual time. Any one Onmyoji can only make, wear, and use one of these wondrous items at a time, and if it is lost or destroyed, the Onmyoji can pay the 200 gold value and the two hours ritual time to make another. 

Spell Focus Adept

10th level Onmyoji class feature

At 10th level, when you cast a spell using an arcane focus, you gain many advantages. When casting a spell using an arcane focus, you gain a +1 magic bonus to the spell attack roll and the save DC increases by +1. These bonuses improve to +2 at level 15, and +3 at level 20. Additionally, spells you cast using an arcane focus ignore partial cover, and at level 15, such spells ignore half-cover.

Master of The Jade Calendar

14th-level Onmyoji feature

At 14th level, you learn to craft the last, greatest focus the Onmyoji utilize, the Jade Calendar Tablet. This is a 10 pound slab of dense clay sheathed in jade gemstone is held through the hole in the center of its octogonal shape, with small beads and moving parts, which are shifted into different positions by hand to make calculations and demonstrate astronomical movements. This is produced in a one hour ritual costing 500 gold in jade and supplies, and the tool is used to create entirely new and powerful spell effects for the Onmyoji when used as an arcane focus. 

When you cast a spell using the Jade Calendar Tablet, you may choose to cast that spell as if you had expended one higher level spell slot to cast it, without spending any higher spell slot than the original spell. For example, you may spend a 3rd level spell slot to cast Lightning Bolt, and it will deal an additional 1d6 damage as if it were cast with a 4th level spell slot. If you choose to cast a spell using a higher level spell slot than its original level, you may also use this feature to cast that spell as if it were one spell level higher than the spell slot you expended, up to a maximum of affecting 8th level expended spell slots with this ability. You may use this feature a number of times equal to your Intelligence modifier before you must finish a long rest to use it again. If you use the Jade Calendar Tablet to cast a 9th-level spell, roll a d20, and if your roll a 19 or 20, you regain an expended spell slot of 8th level or less.

Additionally, whenever any spell requires a specific focus in its description (such as a small glass rod), you may substitute any of your arcane foci to empower that spell.