Chronometric

A chronometric is a warrior, that is genetically susceptible to the cycle of day and night. They come in the varieties Daywalker and Nightstalker, gaining boost by day and night respectively. Originally they were the result of natural mutations, but soon were researched and bred by illicit parties for particular mercenary work.

Daywalkers are strongest by day and later gain features that help on the front line, weakening their enemies. Nightstalkers have more power by night and later are best as a mobile unit, giving their allies benefits.

Thematically this archetype feels more like an extension to your race, rather than a profession. 

Chrono Meter

At 3rd level, your chronogene mutation manifests. Choose one of the following options: Daywalker or Nightstalker. This choice is made once and is in effect for all subsequent features.
As a Daywalker you gain benefits during the day, as a Nightstalker during the night. As part of this mutation, you can always tell whether it is day or night, even underground.

Daywalker

As a Daywalker you can tell if it is before high noon or after.
Also, you gain the light cantrip, but don't require VSM to cast it.

Nightstalker

As a Nightstalker you can see in darkness as if it were daylight.
Also, you can tell if it is before midnight of after.

Chrono Dependence

Choose an ability. In your preferred phase, every time you use this modifier for attacks, checks and saving throws, you can add it again. In the other phase you subtract it (leaving you with a net zero). You can change your choice of ability every time you complete a short or long rest. The ability modifier must be positive to be eligible.

For instance, if you choose Strength and have a score of 14 at 3rd level, your normal attack bonus of 4 (2 modifier + 2 proficiency) would increase to 6 (4 modifier + 2 proficiency).

Chrono Endurance

Starting at 7th level, you can let the aura of day or night flow into you. In your preferred phase you can use a Bonus Action to heal a number of Hit Points equal to your Constitution modifier + your Proficiency bonus at the start of your turn for 1 minute. In the other phase this is reduced to only your Constitution modifier. The effect doesn't end early when you fall unconscious, but you heal only, if you stabilize within the duration of this feature. You don't heal while you have to make Death Saves.

You can use this feature once. To use it again you must complete a long rest.

Chrono Genesis

Starting at 10th level, you can create an environment, that suits you, regardless of the time of day.

Daywalker

As a Bonus Action you gain the effect of the Daylight spell with the following parameters:
Range self/30ft, duration 10 minutes, level 4 regarding cancellation, no VSM or concentration required.
For the duration of this effect you gain the benefits, as if it were day.
The effect doesn't require concentration, but ends if you fall unconscious.

You can use this feature 3 times. To use it again you must complete a long rest.

Nightstalker

Starting at 10th level, you gain the effect of the Darkness spell as a Bonus Action with the following parameters:
Range self/30ft, duration 10 minutes, level 4 regarding cancellation, no VSM required.
For the duration of this effect you gain the benefits as if it were night.
The effect doesn't require concentration, but ends if you fall unconscious

You can use this feature 3 times. To use it again you must complete a long rest.

Chrono Mobility

Starting at 10th level, you get more mobile, while in your preferred phase.

Daywalker

As a Daywalker, your speed increases by 20ft.

Nightstalker

As a Nightstalker, while in your preferred phase, you can us a Bonus Action to teleport to an unoccupied space within 30ft.

Chrono Enhancement

Starting at 15th level, you can project the aura of your preferred phase on your environment.

Daywalker

Every hostile creature within your Chrono Genesis area (30ft) gets the following properties:

- Any ranged attack (weapon or spell) against the creature has Advantage.
- The creature has Disadvantage on melee attacks against you, unless it has Blindsight.

This effect also works, when Chrono Genesis is used by day.

Nightstalker

Every ally within your Chrono Genesis area (30ft) gets the following properties:

- can see normally through your darkness spell area
- increase of speed by 20ft

This effect also works, when Chrono Genesis is used by night.

Chrono Master

Starting at 18th level, you master the influence of the phases. In you preferred phase, you can add your modifier bonus for every ability on attacks, checks and saving throws. No choice needed after a rest. In the other phase, you no longer suffer the penalty.