Magic

All practitioners of magic access it and understand it in a different way, but there are a few universal concepts, so rather than describe them redundantly in every class description, they will be described here.

Mana

Mana is the energy source for all spells. As a rule, spells cost 1 Mana to cast per level of the spell (and cantrips are free), although always check the spell description to be sure. When you're out of Mana, you can't cast spells anymore.

Your class description will tell you how much mana you have. Classes like Wizard, Witch, Warlock, Druid, and Cleric typically gain 2 Mana per level, while a more hybrid caster like Bard might get less Mana. Non-casting classes such as Fighter and Rogue get no Mana per level.

Casting Skills

There is no general skill for practicing magic--it's not something just anybody can do. Instead, there are a variety of skills, each specific to a casting class, each with its own unique way of understanding and working with magic, applying some advantages and some disadvantages to the craft. Each class description contains the authoritative skill, but here are the ideas at a high level:

• Clerics use Faith (Wis), which is an expression of the faith in their divine source. Because faith is not based on knowledge, but rather conviction, clerics tend to gain access to magic through increased closeness with their divine source, rather than by studying scrolls and traversing tomes. They can't absorb new knowledge that way, but they can occasionally call upon their faith to perform acts of divine intervention that aren't possible with the spells on their list alone.
• Druids use Bond (Wis), which, similar to faith, expresses the bond they share with nature and the elements. Druids typically do not play favorites with one element or the next (although talents do exist), but rather respect the natural order of their environment. Like Clerics, Druids can call upon their bond in a time of need, but the benefits will be specific to the elemental balance that prevails in their region--it's no use begging nature to create an avalanche of snow in the middle of a desert.
• Sorcerers use TBD (Cha), which is simply an innate understanding of magic, often defying description, and typically impossible to transfer to others. Since magic comes relatively easy to Sorcerers, they have little difficulty mastering new powers, but are slow to discover them, as they benefit little from arcane writings and lectures. The powers they do command they master to such extent that they can modify them in small ways to customize them to the need at hand.
• Warlocks use Pact (Cha), which is similar to Bond, but not so much based on trust and kinship as it is on competing wills. The beings and forces with which warlocks form Pacts are extremely willful, and their will usually isn't in the best interest of the warlock. Still, they command vast amounts of power, and can make it worth the warlock's time to clash wills with them. Their special ability is that their Pact-bearer is always at hand if they need just a bit more power...for a price.
• Witches use Sympathy (Wis), a deep and humble understanding of the sympathetic nature of magic. Witches know that no spell exists in a vacuum, that no weal or woe worked by magic vanishes from the system, but is rather transmitted through the interconnected mass of all living things, until inevitably it revisits its originator. This gives them the special ability to sense--and even exploit--the karmic "debt", as it were, that any given practitioner has accumulated through their works.
• Wizards use Arcana (Int), a skill representing knowledge of glyphs, words, formulae and the like, necessary to express magical effects (at least the way wizards think about them). Spellcasting through Arcana is a very cognitive process, rewarding the strongest intellects. Because wizards use a mostly standardized set of equations, nomenclature, etc, notes from one wizard are usually legible to another, allowing the transfer of knowledge between wizards.

This system is open to further flexibility. For example, warlocks might choose Contract (Int) instead of Pact (Cha), a skill more about outsmarting their pact-bearer through fine print and legal minutiae. Another warlock, with a very interesting relationship to his power source, might use Bond or even Faith. A strange sort of Cleric or Druid might use Pact.

Skill Mechanics

Casting skills are skills, meaning they work as all 5e skills do. Rolling a skill check means rolling 1d20 + ability modifier + proficiency bonus.

All uses of magic require a skill check, just like all attacks require an attack roll. Save DCs still exist, but are set by this roll, rather than a passive number. Thus, spellcasting actions work as follows:

• Declare which spell you're casting
• Roll your casting skill check
• If the spell is targeted (e.g. a ray or touch), your roll opposes the target's AC. Such spells can critically hit.
• If the spell is an area spell, there is no need to hit an AC, but the spell also cannot critically hit.
• If the spell has no targeting at all, it is still necessary to roll. A natural 1 reflects a critical failure, which leads to a miscast (see below), and the roll establishes the DC to any saves allowed by the spell, in addition to any dispel or counterspell attempts an enemy might make.

Counterspelling

If someone is casting a spell, and you want to prevent them from doing so, you have several options to initiate a Counterspell:

• If you have actions available this turn, you can take an action to Counterspell, as long as your Initiative roll exceeds your opponent's
• If you ready an action to Counterspell, you may use that action without needing to pass an Initiative check
• If you ready a spell, you may use that spell to Counterspell without needing to pass an Initiative check

Once you've initiated a Counterspell, here's how it works:

• To counter a spell, you must cast a spell. Your chance of success is greater the closer the spell you're using is to what your opponent is using.
• If you're using the exact same spell, you win automatically.
• If you're using a different spell, but successfully argue that it would be a good counter (e.g. Fireball to counter a Wall of Ice), you may attempt an opposed casting skill check (see below).
• If you're using any other spell in the same discipline, you can roll an opposed casting skill check (see below) with disadvantage.

If you require an opposed casting skill check to succeed, resolve it as follows:

• Roll your casting skill check as normal
• It is opposed to the DC of the spell you're countering (established when the caster rolled his own check to cast it)
• Apply any modifiers from above
• Apply a modifier based on Mana cost
  • If your spell cost 4, and your opponent's cost 5, your check is at a -1
  • If your spell cost 8, and your opponent's cost 4, your check is at a +4

If you succeed, your opponent's spell is nullified, as it it were never cast. You both still spent Mana and actions on the spells you used.

If you fail, your opponent's spell succeeds, as if you hadn't attempted to Counterspell, and your spell has no further effect.

Dispelling

Dispelling works just like Counterspelling, but against a spell that has already been cast, and is currently active (concentration or active duration).

Miscasting

If you critically fail on any casting check, you suffer a miscast.

Rules TBD. For now let's just do a wild surge roll.

Spell Lists

There is no longer such a thing as a "wizard spell list" or a "warlock spell list" or the like. Rather, all spells exist within a single framework, and each class gains access to some portion of the global spell list.

Spells are organized first into Schools, then into Disciplines. For example:

• Fireball is part of the Discipline of Fire within the School of Elementalism.
• Dimension Door is part of the Discipline of Teleportation within the School of Conjuration.
• Immolate is part of the Discipline of Infernal within the School of Invocation.

When two classes' spell access overlap, the spells they share are identical. No two classes will treat the same spell differently; for example, there are no cases where a wizard gets a spell at level 4, and a druid gets the exact same spell at level 7.

Upgrades

Spell lists contain more than just new spells: they also contain upgrades to previous spells.

For example, the spell [Frost Block] encases the target in a block of ice, rendering them invulnerable, but unable to attack. Right next to it, within the Frost discipline in the Elementalism school, is the upgrade [Reactive Frost Block], which augments Frost Block, making it a reaction triggered by an attack on you, but changing the target to self-only.

Note that all upgrades are optional; each time you cast the spell, you can decide to apply none, some, or all of your upgrades to that specific casting.

Upgrades do not affect counterspelling or dispelling, unless specifically noted, or unless they modify Mana cost (which is normally part of the process).

Bindings

Like Upgrades, Bindings appear on the spell list, but they are not spells. Rather, they are permanent magical abilities, that come at a cost. Each binding's description will say something like "binds 3 mana". This means that if you learn the Binding, you permanently reduce your maximum Mana by 3, in exchange for the new, permanent ability.

You haven't really "lost" the Mana, but rather you are reserving a portion of your magical energy to power an always-on (or otherwise consistently available) ability.

You can conduct a ritual to un-bind Mana, in exchange for losing the power that came with it. The ritual takes 1 day, and causes disadvantage to all casting checks for another day. This does not entitle you to learn a new one in its place. You still "know" the Binding, you've just disabled it. You can conduct a variant of the same ritual to re-enable a binding, at the same cost.

Schools

• Arcana
• Divination
• Conjuration
• Holy
• Illusion
• Invocation
• Mentalism
• Necromancy
• Thaumaturgy

Rituals

Quick notes:

• 3 costs/tests
  • Max mana (based on level/group size/multipliers such as time of day, place, time of year, etc)
  • Endurance (suffer HP loss, ability strain, saves, etc)
  • Skill check (based on level/group assist/skills)
• Fuel (aka Mana cost) is relatively minor, as it can be easily supplied via assistants, items, etc