How does the Silver Spear item work: do you still roll, and when do you decide to use it?

Question

Accepted Answer

You move your Dexterity token up one placement and still roll. Successes are counted on the Dexterity track instead of the usual track, and you can decide to use the item after the roll.

Destinies

How does the Silver Spear item work: do you still roll, and when do you decide to use it?