The Avengers, Vol. 2 #1B (1996) Newsstand

Awaken the Thunder!
The Avengers have been formed, and are ready to protect the world under the guidance of Nick Fury. Loki learns of this, and also learns that Thor is trapped in a very potent amber. He lures the Avengers there, allowing them to free Thor. Loki then convinces Thor that the heroes are actually his mortal enemies, and that they are responsible for his captivity.
Release Date: 1996