BattleTech: Tactical Operations Advanced rules
Take your warfare to a whole new level of excitement! Deploy under cover of exotic weather and severe planetary conditions. Surprise your enemy with your mastery of new battlefield tactics -- from artillery to command-level comms to minefields! A daring commander can take advantage of any or all of these, if they're brave enough to seize the moment!
Tactical Operations: Advanced Rules is the one-source reference for advanced rules that apply to on-world operations. It includes new movement and combat options.