Death Grip is a 25th level swordmage Daily power that was introduced in the 372nd edition of Dragon (magazine).
Death Grip
Swordmage Attack 25
You assail your foe as a distraction while a crushing hand of shadows closes its grip around your enemy.
Melee weapon
Target: One creature
Attack: Intelligence vs. AC
Hit: 2[W] + Intelligence modifier damage, and you make a secondary attack with combat advantage against the same target.
Miss: You make the secondary attack against the target.
Secondary Attack: Intelligence vs. Reflex
Hit: Ongoing 10 necrotic damage, and the target is restrained and cannot teleport (save ends all).
Miss: Ongoing 5 necrotic damage (save ends), and the target is restrained and cannot teleport until the end of your next turn.