"If a card effect uses the word 'cannot', that effect is absolute." RR, p.1 The Golden Rules

I believe Jaina's Light effect is "absolute".

"Each effect in the game has a timing during which it can resolve. "

I believe both these effects have the same timing resolution, in Attack Step 1, Declare Target. "Measure line of sight to the defender to ensure the attack is possible and to determine if it is obstructed." We are told in this step to determine if the attack is "obstructed" and reference the definition. There is no other step to determine "obstructed" so the both effects' timing must be resolved during this step.

Montferrat's effect requires us to use the "obstructed" definition but it conflicts with it as the requirements of "line of sight", "obstacle token", or "another ship" are not mentioned in the effect. We are told to "treat the attack as obstructed" which supersedes the requirements in the definition, so the attack is obstructed. This effect is resolved. Jaina's Light effect's timing is also in this step. It is resolved. Since the timing of these two effects conflict in the same step, The Golden Rule applies.

Both effects have been resolved, but there has been discussion about the "application" of the Obstructed rule. We are told to apply the "Obstructed" rule during the "Roll Attack Dice" step: "If an attack is obstructed by one or more ships or obstacles, the attacker must choose and remove one die from his attack pool before he rolls dice during the (Attack Step 2,) “Roll Attack Dice” step. However, it was "resolved" in Attack Step 1, the attack was not obstructed, so the "Obstructed" rule is not applied during this step.

"Each effect in the game has a timing during which it can resolve. "

I believe both these effects have the same timing resolution, in Attack Step 1, Declare Target. "Measure line of sight to the defender to ensure the attack is possible and to determine if it is obstructed." We are told in this step to determine if the attack is "obstructed" and reference the definition. There is no other step to determine "obstructed" so the both effects' timing must be resolved during this step.

Montferrat's effect requires us to use the "obstructed" definition but it conflicts with it as the requirements of "line of sight", "obstacle token", or "another ship" are not mentioned in the effect. We are told to "treat the attack as obstructed" which supersedes the requirements in the definition, so the attack is obstructed. This effect is resolved. Jaina's Light effect's timing is also in this step. It is resolved. Since the timing of these two effects conflict in the same step, The Golden Rule applies.

Both effects have been resolved, but there has been discussion about the "application" of the Obstructed rule. We are told to apply the "Obstructed" rule during the "Roll Attack Dice" step: "If an attack is obstructed by one or more ships or obstacles, the attacker must choose and remove one die from his attack pool before he rolls dice during the (Attack Step 2,) “Roll Attack Dice” step. However, it was "resolved" in Attack Step 1, the attack was not obstructed, so the "Obstructed" rule is not applied during this step.

But this logic ignores the timing rule regarding if both players have an effect that triggers at the same time, that the first (initiative) player resolves effects first. This might be a case were 'cannot' gets trumped by timing.

But this logic ignores the timing rule regarding if both players have an effect that triggers at the same time, that the first (initiative) player resolves effects first. This might be a case were 'cannot' gets trumped by timing.

If there is a direct interaction, then Cannot cannot be trumped by Timing, or the Golden Rule is not a Golden Rule.