Mask, Stalker’s

[Gilborn]

Hi,
we had e little problem.
If a Charakter wears the Mask he can take the appearance of any creature of the wearer’s basic size and shape within 60 feet that he observes.
But in our group the wearer observed the creature an then the creature leaves the room an went out.
2 rounds later, the wearer want to take the appeareance of theses creature. Befor he said that he observes theses creature.
Is this possible?
Ob must the creature stay in the room at the moment the wearer want take the appearance of the creature an must he see the creature at this moment.

I think the wearer must see the creature an the creature must stay within 60 feet.

Sorry for my english but i hope you understand.

[StabbittyDoom]

The item description says "observes" not "has observed", so he has to be observing it at the time that he takes the full-round action.

d20pfsrd wrote:

Preserved sections harvested from several different human faces cover this mask.

When worn, the mask desaturates the wearer’s color, making him appear shadowy and granting a +5 competence bonus on Stealth checks. Once per day as a full-round action, the wearer can cause the mask’s features to take on the appearance of any creature of the wearer’s basic size and shape within 60 feet that he observes, allowing the wearer to adopt that creature’s appearance for 1 hour. This grants him a +10 bonus on Disguise checks made to appear as the creature. The mask also grants the wearer a +1 bonus on attack rolls and weapon damage rolls made against the creature he is disguised as, as the mask builds upon the wearer’s rage and jealousy of the target’s appearance.