Thunder Shells, also known as FASCAM Shells, are variations on Thunder LRMs developed by the Terran Hegemony in 2621. Fired by Long Tom, Sniper and Thumper artillery, FASCAM shells went extinct in the Inner Sphere during the Succession Wars until the Clan Invasion. It was then recovered by the Capellan Confederation in 3051, who would also create variations that deployed Anti-Jump "Active" Mines and Vibrabombs in 3056.
Thunder Shells follow the standard artillery rules, however instead of dealing direct damage they deploy a minefield onto the target hex. The density of the minefield is dependent upon which artillery piece fired it. Units within a hex struck by a Thunder bomb may exit the minefield without damage, however other units passing through it follow the standard minefield rules.
- Tactical Operations, p. 357