[BT] Critical Hit Effects

AMMUNITION
If a critical hit destroys a slot carrying explosive ammunition, the ammo explodes (all ammunition is explosive unless specifically noted otherwise). The MechWarrior takes 2 points of damage as a result of the feedback received through their neurohelmet. In addition, the ’Mech takes damage to its internal structure.
A critical hit to an ammo slot only explodes the ammo in that slot. Exploded ammo deals damage equal to the Damage Value done by one turn’s worth of shots. For example, the ammo per shot of a machine gun slot has a Damage Value of 2, an LRM-15 a Damage Value of 15, and a SRM-6 a Damage Value of 12. Apply the resulting damage to the Internal Structure Diagram.
Because an ammunition explosion damages the internal structure of the location where it explodes, a roll to determine critical hits is necessary; i.e. an ammo explosion could cause another ammo explosion, inflicting 4 points of damage on the MechWarrior.
Empty Bins: If an empty ammunition slot takes a critical hit, the hit is still applied there, but no further damage or effects occur.

ARM BLOWN OFF (ARM)
This critical hit occurs when the player rolls a 12 on the Determining Critical Hits Table for an arm hit, and is automatic (neither player may choose to roll the three critical hits instead). The hit blows the arm off.
When an arm is blown off in this way, explosive components in that arm do not explode.
An arm blown off by a critical hit remains in the hex in which it was lost and may be used as a club.

COCKPIT (HEAD)
A critical hit to the cockpit destroys that slot, kills the MechWarrior, and destroys the ’Mech. Remove the ’Mech from the map in the end of the phase in which it was destroyed.

ENGINE (TORSO)
’Mech engines have 3 points of shielding. Each critical hit to an engine slot destroys 1 point of shielding. As shielding is destroyed, the amount of heat escaping from the ’Mech’s fusion drive increases.
The first hit increases the ’Mech’s heat build-up by 5 points per turn. The second adds another 5 points of heat build-up per turn for a total of 10 points per turn. A ’Mech is destroyed if it suffers three engine hits (remember to count engine slots present in the ’Mech’s side torsos, if any). Remove the ’Mech from the map at the end of the phase in which it was destroyed.

FOOT ACTUATOR (LEG)
This critical hit destroys the muscle (actuator) in the foot. For each foot actuator damaged, reduce the ’Mech’s Walking MP by 1. Recalculate its Running MP accordingly by multiplying the new Walking MP by 1.5, rounding up.
PSR Modifiers: +1 each. The ’Mech’s controller must make a PSR at the end of the phase in which the critical hit occurred. Additionally, a PSR is required whenever the ’Mech jumps; the roll is made at the end of the ’Mech’s movement.
Target Number Modifiers: +1 to all kick attacks.

GYRO (TORSO)
The gyroscope keeps the ’Mech upright and able to move. The first hit to a gyro damages it, and the second destroys it.
When a ’Mech’s gyro is destroyed, the ’Mech automatically falls and cannot stand up again; the usual Piloting Skill Roll made to avoid damaging the MechWarrior in the fall applies a +6 Target Number modifier for the destroyed gyro.
’Mechs with a destroyed gyro may make weapon attacks per Firing While Prone, and may change facing by one hexside per turn provided they have at least 1 MP available. A ’Mech with a destroyed gyro is not considered immobile.
PSR Modifiers: +3 if damaged, +3 if destroyed (cumulative). The controlling player must make a PSR when the first critical hit occurred, unless the ’Mech received a second gyro hit in the same phase (in which case it automatically fell and so the PSR is unnecessary). Additionally, a PSR is required every time the ’Mech runs or jumps; the roll is made at the end of the ’Mech’s movement.

HAND ACTUATOR (ARM)
A critical hit to the hand actuator destroys the muscles controlling the ’Mech’s wrist and hand. The ’Mech can no longer make physical weapon or clubbing attacks with that arm.
Target Number Modifiers: +1 to all punches made with that arm.
Missing Actuators: Some ’Mechs are designed without one or both hand actuators. The Target Number modifier for punch attacks given above still applies to such ’Mechs (i.e. whether the actuator is destroyed or merely absent is irrelevant).

HEAD BLOWN OFF (HEAD)
A hit blows off a ’Mech’s head when the player rolls a 12 on the Determining Critical Hits Table for the head hit location.

HEAT SINKS
A critical hit to a heat sink destroys it and reduces the ’Mech’s ability to dissipate heat. For example, if a ’Mech with 16 single heat sinks has three of its heat sinks destroyed, it can now only dissipate 13 points of heat per turn.

HIP (LEG)
A critical hit to a hip freezes the affected leg in a straight position. The ’Mech cannot make kick attacks. Additionally, its Walking MP is cut in half (round up; apply before any leg or foot actuator damage MP reductions). Recalculate its Running MP accordingly by multiplying the new Walking MP by 1.5, rounding up.
After a hip critical hit, ignore any other critical hit modifiers from previous turns due to damage on that leg (even if this actually reduces the PSR penalty provided by the leg). However, other critical hits applied to that leg on this turn or later still apply.
A critical hit to the second hip reduces the ’Mech’s MP to 0, but the ’Mech is not considered immobile.
PSR Modifiers: +2 per hip critical hit; this modifier overrides all other critical hit modifiers from that leg. The controlling player must make a PSR at the end of the phase in which the critical hit occurred. Additionally, a PSR is required every time the ’Mech runs or jumps; the roll is made at the end of the ’Mech’s movement.

JUMP JET (LEG/TORSO)
For each critical hit to a jump jet, reduce the ’Mech’s Jumping MP by 1.

LEG BLOWN OFF (LEG)
This critical hit occurs when the player rolls a 12 on the Determining Critical Hits Table for a leg location hit, and is automatic - the player may not choose to roll the three critical hits instead.
When a leg is blown off in this way, explosive components in that leg do not explode.
A leg blown off by a critical hit is left in the hex it was lost in and may be used as a club.

LIFE SUPPORT (HEAD)
Any critical hit knocks out this system permanently and leaves the pilot vulnerable to increased heat; the other critical slot can still take damage, but the hit has no additional effect. The MechWarrior takes 1 point of damage at the end of every Heat Phase that the ’Mech’s Heat Scale is between 15 and 25; if the Heat Scale is 26 or higher, the MechWarrior takes 2 points of damage instead.

LOWER ARM ACTUATOR (ARM)
This critical hit destroys the actuator in the ’Mech’s lower arm. Damage from punches with this arm is halved (round down).
Target Number Modifiers:
• +1 to all weapons firing from that arm.
• +2 to any punches or physical weapon attacks with that arm.
• +2 to all clubbing attacks.
Missing Actuators: Some ’Mechs are designed without one or both lower arm actuators. These ’Mechs do not suffer the weapon attack modifier for the missing actuators, though the modifiers for damage reduction and physical attacks still apply.

LOWER LEG ACTUATOR (LEG)
This critical hit destroys the muscle (actuator) in the lower leg. For each lower leg actuator critical hit, reduce the ’Mech’s Walking MP by 1. Recalculate its Running MP accordingly by multiplying the new Walking MP by 1.5, rounding up.
Additionally, for each lower leg actuator critical hit, all kick attacks inflict half the standard damage (round down).
PSR Modifiers: +1 each. The controlling player must make a PSR at the end of the phase in which the critical hit occurred. Additionally, a PSR is required every time the ’Mech jumps; the roll is made at the end of the ’Mech’s movement.
Target Number Modifiers: +2 to all kick attacks.

SENSORS (HEAD)
Critical hits to a ’Mech’s sensors make weapon attacks increasingly difficult. Critical hits to sensors do not affect other electronic equipment mounted by the ’Mech (such as ECM, C3, and so on), or physical attacks.
Target Number Modifiers: +2 to all weapon attacks after the first hit. A second sensor hit makes it impossible for the ’Mech to fire its weapons. In both cases, physical attacks are unaffected.

SHOULDER (ARM)
A critical hit to this actuator freezes the shoulder joint. The ’Mech may not punch or make physical weapon attacks with that arm, nor may it make clubbing attacks.
Target Number Modifiers: +4 to all weapons firing from that arm (overrides all other weapons fire modifiers from critical hits to that arm).

UPPER ARM ACTUATOR (ARM)
This critical hit destroys the actuator in the ’Mech’s upper arm. Damage from punches with the arm is halved (round down).
Target Number Modifiers:
• +1 to all weapons firing from that arm.
• +2 to all punches and physical weapon attacks with that arm.
• +2 to all clubbing attacks.

UPPER LEG ACTUATOR (LEG)
This critical hit destroys the muscle (actuator) in the upper leg. For each upper leg actuator damaged, reduce the ’Mech’s Walking MP by 1. Recalculate its Running MP accordingly by multiplying the new Walking MP by 1.5, rounding up.
Additionally, all kick attacks inflict half the standard damage (rounding down).
PSR Modifiers: +1 each. The controlling player must make a PSR at the end of the phase in which the critical hit occurred. Additionally, a PSR is required every time the ’Mech jumps; the roll is made at the end of the ’Mech’s movement.
Target Number Modifiers: +2 to all kick attacks.

WEAPONS AND EQUIPMENT
When a weapon or piece of equipment receives a critical hit, it is rendered useless for the remainder of the game. If the item takes up more than one critical slot, its remaining slots are not also marked off: each can still be hit by subsequent critical hits. This has no effect other than to absorb the critical hit.
For example, a PPC fills three critical slots. The PPC is disabled as soon as one of its three critical slots takes a hit, leaving its remaining two slots able to take critical hits but otherwise resulting in a useless weapon.
Explosive Components: Certain items or weapons, such as Gauss rifles, will create an ammunition explosion when they receive their first critical hit. Whether an item created an explosion (and how much damage this causes) is indicated in each item's description in the Weapons and Equipment chapter. In all other respects, the critical hit is treated in the same manner as above.