Stealth Fighter, Phantom Fighter
Until they perform their X action, all weapons systems ignore them.
If the Phantom Fighter is targeted by a rocket (after it has revealed itself) the rocket is destroyed with no effect.
Cryoshield Fighter, Cryoshield Frigate
The cryoshield absorbs all damage the first time the threat is targeted. In the first Compute Damage step in which the threat is targeted by at least one weapon, the threat is not damaged, regardless of its shield points and the total strength of your weapons. Instead, put a black block on its cryoshield icon to denote that the cryoshield has been destroyed. In later turns, the threat can be targeted and damaged as normal.
Compute the result of the attack at the specified strength, but draw 2 damage tiles (instead of 1) for each point of damage that gets through the shield.
Energy Cloud, Maelstrom
If the threat is in range of the pulse cannon and the pulse cannon is fired, the threat's shield points are 0 for that turn. The pulse cannon also does damage as normal. On subsequent turns, the threat will again have the number of shield points specified on the card (unless hit by the pulse cannon).
A heavy laser cannon will ignore the Scout, instead targeting the nearest other threat on its trajectory.
Once the Scout performs its X action, all other external threats have +1 strength on their attacks until the Scout is destroyed. (Threats which are higher numbered than the Scout will get this +1 bonus on that same turn.) This bonus applies to all attacks (including the special attacks of Nemesis and Asteroids) and even applies to threats that did not appear before the Scout's X action. If the Scout performs its Z action (i.e., is not destroyed) this bonus lasts to the end of the mission.
As soon as the Scout performs its Y action, move the other threats ahead 1 square. They move in order, according to their numbered tokens. If a threat advances onto an X, Y, or Z square, it performs the indicated action immediately.
The Swarm can only be destroyed by hitting it on 3 separate turns, regardless of the strength of the weapons that target it. (Exception: Swarm can get two damage on the turn Leviathan Tanker is destroyed).
The -2 shield points means that if the Jellyfish is targeted, you add 2 points to the strength of the attack instead of subtracting. Of course, if it is not targeted, it takes no damage.
Once the Marauder performs its X action, all external threats (including the Marauder) have +1 shield point until the Marauder is destroyed. This bonus even applies to threats that do not appear until after the Marauder's X action. If the Marauder performs its Z action (i.e., is not destroyed) this bonus lasts to the end of the mission.
When the Leviathan Tanker is destroyed, all external threats get an extra red block, regardless of shield points and special effects. (So untargetable threats, cryoshielded threats, and even the Swarm will also take a point of damage).
Psionic Satellite, Pulse Satellite
If a Satellite is at distance 3, all weapons systems ignore it.
Interceptors targeting only the Behemoth have strength 9 instead of strength 3. The player leading them is knocked out when computing damage done to the Behemoth and his or her battlebot squad is disabled for the rest of the mission. This will give your crew a -3 score penalty and prevent other players from taking out interceptors on this mission. The heroic battlebot action increases the interceptors' strength to 10, but the player will still be knocked out and the squad will still be disabled.
If there is at least one other threat at distance 1, the interceptors will attack all such threats, including the Behemoth, with the usual strength 1, and the player will not be knocked out.
If the Juggernaut is on a trajectory, rockets ignore all other threats. They will always target the Juggernaut, even if it is out of their normal range. The Juggernaut gains +1 shield point after the rocket's damage to it has been computed.
The Nemesis attacks all zones at the end of any Compute Damage step in which it gained at least 1 red block (even if the block came from a destroyed Leviathan Tanker). The Nemesis takes damage from its own X and Y actions. This damage ignores its shield points. If the Nemesis destroys itself in this way, it still counts as a destroyed threat and the captain keeps the card as a trophy.
If the Nemesis performs its Z action, you lose. The fact that the Nemesis is also destroyed might be some consolation, but you don't get any points for losing.
Minor Asteroid, Asteroid, Major Asteroid
At the end of any Compute Damage step in which an Asteroid is destroyed, it performs an attack based on the number of X and Y squares it has already passed (or landed on). If there are multiple such attacks, they are dealt with in order, starting with the threat with the lowest numbered token.