A friend of mine has been planning to run a game based on the trails game series and has proposed some interesting rules for the arcus units.

I realize the amount of crossover in the people interested in 5e and trails is probably very small so let me explain. An arcus unit is a small device that allows humans to channel the same magic monsters do. The unit uses small marbles called quartz, refined from rare minerals called sepith, to grant these powers. This is almost the only way to use magic as a human.

Charge points and prepared spells:

• Use the DMGs spell points optional rule but call them charge points.
• Every character can prepare up to six spells by placing quartz into their arcus units. These quartz can be exchanged for others that the character possesses upon completing a short or long rest.
• Quartz are magic items and not tied to any specific class, classes do not learn spells on their own and are unable to prepare them without quartz.
• The maximum spell level a character can prepare is the highest spell slot they would have at their level. For classes that do not normally cast spells they follow the same third spell progression as eldritch knight and arcane trickster.

Quartz magic item rarity

Casting rules changes:

• Classes that do not usually cast spells use the same third progression as eldritch knight and arcane trickster (including charge points) however unless they are; eldritch knight, arcane trickster, or four elements they do not add their proficiency bonus to their spell attack modifier or spell save DC. for these classes they choose weather their casting ability is; intelligence, wisdom, or charisma
• After casting a spell the character enters a delay period

Delay period:
After casting a spell there is a delay before it takes effect, during this time they are concentrating on the spell, if they lose concentration before the spell takes effect then the spell fails.

The delay period depends on the spell level and caster status of the character. Once calculated as described below, create a marker on the initiative that is the character’s initiative minus the delay, that marker is when the spell takes effect.

Calculating delay:

• Non / third caster Delay = 2x spell level

• Half caster Delay = spell level

• Full caster Delay = 1/2 spell level