Scarlet Walker's Blood-Draining Gaze

[mtg3992]

Blood-Draining Gaze (Su) All creatures within 20 feet of a scarlet
walker are subject to the monster's eerie blood-draining gaze. (p414 RotRL Anniversary Ed)

Is this an attack which the SW has to actually make, or does it just happen if a character is withing 20'?

[mtg3992]

Bumping, as this will likely come up tonight . . . any help out there?

[VRMH]

It follows the universal monster rules for Gaze attacks:

Spoiler:

A gaze special attack takes effect when foes look at the attacking creature’s eyes. The attack can have any sort of effect; petrification, death, and charm are common. The typical range is 30 feet, but check the creature's entry for details. The type of saving throw for a gaze attack varies, but it is usually a Will or Fortitude save (DC 10 + 1/2 gazing creature’s racial HD + gazing creature’s Cha modifier; the exact DC is given in the creature’s text). A successful saving throw negates the effect. A monster’s gaze attack is described in abbreviated form in its description. Each opponent within range of a gaze attack must attempt a saving throw each round at the beginning of his or her turn in the initiative order. Only looking directly at a creature with a gaze attack leaves an opponent vulnerable. Opponents can avoid the need to make the saving throw by not looking at the creature, in one of two ways.

Averting Eyes: The opponent avoids looking at the creature’s face, instead looking at its body, watching its shadow, tracking it in a reflective surface, etc. Each round, the opponent has a 50% chance to avoid having to make a saving throw against the gaze attack. The creature with the gaze attack, however, gains concealment against that opponent.

Wearing a Blindfold: The foe cannot see the creature at all (also possible to achieve by turning one's back on the creature or shutting one's eyes). The creature with the gaze attack gains total concealment against the opponent.

A creature with a gaze attack can actively gaze as an attack action by choosing a target within range. That opponent must attempt a saving throw but can try to avoid this as described above. Thus, it is possible for an opponent to save against a creature’s gaze twice during the same round, once before the opponent’s action and once during the creature’s turn.

Gaze attacks can affect ethereal opponents. A creature is immune to gaze attacks of others of its kind unless otherwise noted. Allies of a creature with a gaze attack might be affected. All the creature's allies are considered to be averting their eyes from the creature with the gaze attack, and have a 50% chance to not need to make a saving throw against the gaze attack each round. The creature can also veil its eyes, thus negating its gaze ability.