Ranged 10
Target: one creature
Attack: Constitution vs. Fortitude
Hit: 2d10 + Constitution modifier thunder damage, and target is removed from play until the end of your next turn. It then reappears in its original space or nearest unoccupied space if that space is occupied.
Star pact: You decide where the target reappears, choosing an unoccupied space within 20 squares of you.
Grasp of Ragnorra is an encounter power available to Warlocks at 27th level, and is designed for use with the star pact. [Dr403:37]
Grasp of Ragnorra was introduced in "Class Acts—Warlock: Strange Constellations" by Bruce R. Cordell in Dragon #403, an article meant to improve the ability for Star Pact warlocks to use Constitution-based abilities at certain levels.
It is an excellent choice for star pact warlocks, as you can potentially place the target in an extremely hazardous position (i.e. 20 feet off the ground for 10d10 falling damage) to inflict the highest potential damage among any available power. Without the pact, it would be a terrible choice.