Picked up a few rules during the Tau game.
Psychic Disciplines; Generating Psychic Powers 40k6 mini-rulebook pg 142
If the Psyker needs to generate more than one psychic power, repeat the above process until a number of psychic powers has been generated equal to the Pysker's Master Level. Note that second and subsequent psychic powers do not have to be generated from the same psychic discipline as the Psyker's first power. If a Psyker generates a power he already has, roll again in the same psychic discipline table until a power is generated that he does not aleady know. It should be noted that different Psykers in the same army can have the same psychic power(s).
Context: When rolling Psychic Powers for the last game opponent said that only half your Psychic Powers can come from one Discipline. Then half to roll from another Discipline. Didn't look it up at the time. Looked this up later.
Vehicles and Overwatch 40k6 pg 76 Re: Gun Drones
Unless specified otherwise, vehicles cannot make Overwatch fire - it takes too long to bring their weapons to bear.
Transports and Assaults 40k6 pg 80
If a Transport vehicle is assaulted, an embarked unit can fire Overwatch at the attackers out its Fire Points.
40k Rulebook FAQ pg 2
Page 80 – Transports, Transports and Assaults. Change the first sentence to read “If a Transport vehicle is assaulted, an embarked unit can fire Overwatch at the attackers out of its Fire Points – note that a unit may still only fire Overwatch once in a turn, even if it is embarked on a Transport.”
4th ed Tau Codex pg 30
While attached, the Gun Drones may fire as part of the vehicle, using their own BS, in addition to any other weapons that would normally be permitted to fire, and are treated as passengers if the vehicle is damaged.
Tau FAQ pg 2
Page 30 – Gun Drones.
At the end of the last sentence ignore “and are treated as passengers if the vehicle is damaged.”
Tau FAQ pg 3
Q. Can gun drones mounted on a vehicle still fire if the vehicle moved too fast, or isn’t allowed to fire its weapons for any other reason? (p30)
A. No, Gun Drones mounted on a vehicle may only fire if the vehicle is allowed to fire at least one weapon. If the vehicle is shaken or stunned, they can only fire Snap Shots.
Context: Devil Fish was assaulted by Eldrad and Friends. It was believed Gun Drones attached to the Devil Fish could perform Overwatch. In the game they did perform Overwatch. Since vehicles cannot perform Overwatch, Gun Drones are unable to perform Overwatch when the vehicle is assaulted. The way this was done in the game was incorrect. Gun Drones performed Overwatch on Eldrad and Friends. They should not have been able to do so per 40k6 pg 76 Vehicles and Overwatch corroborated by Tau FAQ pg 3 link above.
4th ed Tau Codex; Marker Lights sixth bullet point pg 29
To impose a -1 penalty on any Cover Saves the marked unit may have from the effects of the firing unit's shooting. Multiple counters may be expended to impose a cumulative modifier.
Context: Tau used marker lights to reduce Eldrad and friends 2+ (due to Invisibility) to to 4+ cover save. Those marker lights can be mean.