Trap
The weapon
Any weapon that is triggered by a victim through the use of a hidden mechanism.
Often called "booby traps".
Traps never have and never will be allowed in Belegarth, mostly due to the fact that it is impossible to make them in a completely safe manner. (Meaning that no matter how "safe" you make one, it can still be quite dangerous) There are also other reasons why traps aren't allowed.
The tactic
Also a term used to describe the act of surrounding a person or group and ganking them. Usually, the "edge of the world" (the fighting area limitation enforced by marshalls/heralds to keep fighters away from hazards and/or gameplay reasons) is used to execute this maneuver.