Tiefling Shadowcaster and Darkvision

[Chevalier83]

Sometimes, when gaining darkvision it is stated that if you already have it, it is extended by 30 feet. What happens, if it is not explicitely written down?

Shadowcaster 5th level ability replaces a bonus feat by darkvision
Tiefling already has Darkvision

What happens?

[Jeraa]

Chevalier83 wrote:

Sometimes, when gaining darkvision it is stated that if you already have it, it is extended by 30 feet. What happens, if it is not explicitely written down?

Shadowcaster 5th level ability replaces a bonus feat by darkvision
Tiefling already has Darkvision

What happens?

Absolutely nothing. If you already have darkvision, then the shadowcasters Shadowsight ability is wasted, and you get no additional benefit. However, should you somehow lose your racial darkvision (say, by being reincarnated into a different race), then you would still have darkvision because of the Shadowsight ability.

[Cerberus Seven]

Increases to low-light vision always stacks range, increases to darkvision do not unless specified.

[Chevalier83]

Cerberus: do you have a source for that?

[Artanthos]

If you want expanded vision with a tiefling, look at the fiend sight feat.