Open Topped Modifiers

Open-topped: Models embarked on this model can attack
in their Shooting phase. Measure the range and draw line
of sight from any point on this model. When they do so, any restrictions or modifiers that apply to this model also
apply to its passengers...

The last sentence - "Any restrictions or modifiers that apply to this model also apply to its passengers" - what counts as a modifier?

- If a <Kabal> Raider is within 6" of an Archon, it can reroll 1s to hit - presumably this modifier applies to the passengers if they are of the same Kabal, but it looks like it should work even if they aren't of the same Kabal, since the modifier is being applied to the Raider? What if the Raider is a Wych Cult Cabal, but it's near an Archon and a unit inside does match the Archon's Kabal?

- If a unit shoots out of an Obsidian Rose Raider, do they gain +6" range? This looks like a modifier to me. If am Obsidian Rose unit shoots out of its own Raider, do the +6s stack for +12" range?

- If a Dark Creed Raider uses their unique stratagem, it lets it shoot at non-closest characters until the end of the phase. Is this a modifier which can be inherited by its passengers?

After looking at the rule books explanation for modifiers and seeing the example given in the codex it looks as though you can.  This seems like a major over site to me but for all I know it may have been intended.

A modifier is anything which affects the roll or Ballistic Skill.

So yes, if a nearby Archon allows a Raider to reroll 1s, this affects the passengers too.
From the looks of it, yeah. If you shoot outof a Rose Raider, you get tat modifier.
And yes, all modifiers. I guess.

Well now THIS is someting worth FAQing.

EDIT: Personally I'd say a modifier is something that changes your to hit or to wound values. Whereas a reroll is something independant as implicitly stated in the base rules for rerolls : "re-rolls : [...] and re-rolls happen before modifiers (if any) are applied.

So a re-roll is NOT a modifier and it's obvisouly not a restriction either.

Is an increase in range a modifier ? Hard to say but I'd say no. However no solid base on this other than to say that it seems a modifier has to modify a dice roll which is not the case with increased range.

And restrictions should be the interdiction to shoot. So pistol, rapid fire, heavy when advancing for instance or most ranged weapons while within 1" of the enemy.

Now here is a situation where I REALLY don't know what happens : Use Master of the Shadowed Sky, the Flayed Skull stratagem on a Raider/Venom. Now that Raider/Venom has a +1 to hit modifier vs FLY units. Now THIS is an actual modifier for sure, So a unit inside the transport should be affected right ?

Isvan wrote:

Open-topped: Models embarked on this model can attack
in their Shooting phase. Measure the range and draw line
of sight from any point on this model. When they do so, any restrictions or modifiers that apply to this model also
apply to its passengers...

The last sentence - "Any restrictions or modifiers that apply to this model also apply to its passengers" - what counts as a modifier?

But what if the hero is himself mounted on the same boat. Does the boat get affected? For example can an Archon boost the raider and the kabal warriors mounted with him with reroll 1s when he himself is mounted as well.

Stage two of this question... is surrounding units affected as well?

The Transports sidebar on p183 of the rulebook says:
"Embarked units cannot normally do anything or be affected in any way whilst they are embarked. Unless specifically stated, abilities that affect other units within a certain range have no effect whilst the unit that has the ability is embarked."

That means a passenger's aura can't affect the transport, or even the other passengers in the transport, unless they have a rule that specifically states otherwise. Likewise, they don't benefit from any external auras that might be in range of a transport they are in.

EDIT: I just realized the part, "when they do so". So nevermind.