D&D4 Wiki
Preparatory shot
rogue attack 1

Requirement: wielding crossbow, light blade, or sling

Target: one creature

Attack: Dexterity vs. AC

Hit: "Dexterity modifier + Intelligence modifier damage, and the target grants combat advantage to you until the end of your next turn.
"Level 21: 5 + Dexterity modifier + Intelligence modifier damage."[MP2:57]

Preparatory shot is an at-will power available to rogues at 1st level.