Coulson's Revenge is a prototype weapon made from the Destroyer. The weapon was first used in "The Avengers" by Agent Coulson after he was stabbed by Loki. It had enough firepower to propel Loki through the wall. In "Beginning of the End", Agent Coulson uses it once again against Garrett and a couple of supersoldiers. It ultimately didn't kill Garrett (Coulson did that with the Plasma Particle Beam), but definitely packed a punch.
It is also sometimes referred to as "the God-Killer", for its prodigious effect on Loki.