Action question

[Varin Artusk Darkthane]

What type of action to activate I think it would be standard but not sure....

Scarshield (Su)

At 1st level, a scarred witch doctor learns how to harden her mutilated skin, gaining an enhancement bonus to her natural armor bonus equal to 1/2 her class level (minimum +1). She can use this ability for a number of minutes per day equal to her class level. These minutes do not need to be consecutive but she must spend them in 1-minute increments.

This ability replaces the witch's 1st-level hex.

[GhostwheelX]

It's silly (should probably be a swift or free action), but I think it's a standard action as well.

[Imbicatus]

Well, it's two years late, but supernatural abilities are standard actions unless otherwise specified..