Void Signature System
The Void Signature System is a hybrid evolution of Star League era systems such as the Chameleon Light Polarization Shield and the Null Signature System. Essentially a scaled up version of the Word of Blake's Mimetic Armor, the Void Signature System shields a BattleMech's presence from both visual and electronic detection with help from a paired ECM suite.
Introduced by the Word of Blake in 3070 after ten years of research the Void Signature System was rare. Though it was mounted on some unexpected units (including an Archer variant used by the Protectorate Militia), the Void was usually seen on Raptor II variants and in the Shadow Divisions.
One limiting factor for the Void Signature System was its high cost. The base system cost two million C-Bills, but that didn't include the cost of an ECM suite to power it. This restricted the Void System to those units the Blakist commanders could make the best use of it.
 Game Rules
A 'Mech with this system may not mount a Chameleon Light Polarization Shield, Null Signature System, or Stealth Armor. Any Satellite Uplink systems, Targeting Computers or C3 equipment cannot be mounted either.
When the system is active, a 'Mech with the system generates 10 points of heat more than it usually would. When active, the system's stealth ability depends on how much the 'Mech moved, with greater benefits with less movement. However, while the system is active, all shots fired by the unit suffer reduced accuracy.
Like Mimetic Armor, when the Void system is active attacking units gain a to-hit penalty based on the 'Mech's movement. If a Mech doesn't move, the Void system imposes a +3 to hit penalty on the attacker. A Mech that moves 1-2 hexes imposes a +2 to hit penalty, and if the Mech moves 3-5 hexes the attacker suffers a +1 to hit penalty. A Mech that moves 6 or more hexes imposes no to-hit penalty. In addition conventional infantry are less confused by the Void's electronic countermeasure systems and so any to-hit penalty imposed by the Void system is reduced by 1 point. An active Void system is invisible to every electronic probe except the Bloodhound Active Probe.
The void signature system does not weigh a significant amount by itself. However, it does require an ECM suite to be installed to function. The system takes up one critical slot in each of the 'Mech's hit locations except for the head, for a total of seven critical slots. A critical hit to any of these slots (including the ECM suite) will disable the entire system.