Arms of Hadar is a 1st level encounter power for the Warlock class. It was created for the Star Pact, and was introduced in the supplement Arcane Power.
Arms of Hadar
Warlock Attack 1
You call upon Hadar, the Ebon Hunger. Black tendrils erupt from your body and batter nearby creatures, pushing them from you.
Encounter ✦ arcane, implement
Close Burst 2
Target: Each creature in burst
Attack: Constitution vs Reflex
Hit: 1d8 + Constitution modifier damage, and you push the target 2 squares.
Star Pact: You push the target a number of squares equal to 1 + your Intelligence modifier.