Combining Improved Dirge of Doom and Blistering Invective – how long does the “frightened” condition last?

Question

I recently found a pretty neat combination of moves that essentially turns your bard into a freaking jump scare. (Unless your enemies are undead. Or don’t understand your language. Oh well, no trick is perfect…) However, I am a little unsure as to how the fear effects stack, when they run out, etc. The combination goes a follows:

Cast Blistering Invective as a Standard Action

Blistering Invective is a language-dependent Lvl 1 spell that does some fire damage, but more importantly: It allows you to demoralize all enemies in range instead of one at a time.

When you cast this spell, make an Intimidate check to demoralize each enemy within 30 feet of you. Enemies that are demoralized this way take 1d10 points of fire damage and must succeed at a Reflex save or catch fire.

Effects of demoralizing:

If you are successful, the target is shaken for one round. This duration increases by 1 round for every 5 by which you beat the DC.

If it works, your enemies are now shaken for N rounds. (And thanks to your skills and bazillion CHA, an Intimidate check is a piece of cake.)

Start the Dirge of Doom Bardic Performance as a Move Action

By the time you get DoD, starting a Bardic Performances is a move action.

Dirge of Doom (Su): A bard of 8th level or higher can use his performance to foster a sense of growing dread in his enemies, causing them to take become shaken. To be affected, an enemy must be within 30 feet and able to see and hear the bard’s performance. The effect persists for as long as the enemy is within 30 feet and the bard continues the performance. The performance cannot cause a creature to become frightened or panicked, even if the targets are already shaken from another effect.

Now, DoD alone can’t stack fear effects, but with the Improved Dirge of Doom Feat…

The range of your dirge of doom ability is extended to 60 feet. Additionally, if a creature is shaken from another effect, the effect of your dirge of doom is changed to frightened for that specific creature. […] Once affected by this feat, a creature cannot be affected by it again for 24 hours.

Watch your enemies flee in terror

Everybody that was shaken before is now frightened and, as such, has to flee if they are able to do so. No saves allowed! Laugh creepily as they run. Possibly chase after them.

So far so good

However, Demoralize lasts only N rounds and IDoD only affects enemies in a 60ft range. Since frightened opponents flee, the latter is pretty relevant.

Now, as I understand it, the IDoD essentially replaces the Shaken of Demoralize. All Enemies will stay frightened, as long as they are in range and the bard continues the performance – even after the effect of Demoralize runs out.

1. Is this true? Or do enemies still under the influence of DoD return to Shaken after the N rounds of Demoralize are up?

2. What happens to enemies leaving the 60ft range of DoD before the N rounds of Demoralize are over? Are they still Shaken or do they lose all Fear conditions, since Frightened had supplanted Shaken?

3. What happens if somebody leaves the 60ft, but the bard runs after them and “catches” them again?

4. My bard has the “Memorable” Trait. Does this mean enemies will be frightened one additional round, even after they have left the 60ft range? How does this potentially combine with Question 3?

EDIT: My DM has so far allowed my to apply the “Memorable” Bonus on all Bardic Performances. The ruling on this seems unclear, though, so I will bring it up with him. Until then, the question stands: When somebody leaves the range, do they keep fleeing for another round?

Please keep in mind, this isn't about further optimizing this combo or whether it's even all that great. It's about understanding how the conditions work, in order to avoid long and cumbersome debates during fight scenes.

Answer 1

Answers in order

1. The shaken condition caused by demoralizing a foe via the Intimidate skill (facilitated by the blistering invective spell) is replaced by the frightened condition caused by the bard employing a combination of the bard's supernatural ability dirge of doom and the benefit of the feat Improved Dirge of Doom. At least, the condition is replaced for as long as the supernatural ability dirge of doom continues to affect the foe; the affected foes remain demoralized—that duration continuing alongside yet subsumed by the dirge of doom effect—but not also technically simultaneously shaken as fear conditions escalate.

   That is, the supernatural ability dirge of doom doesn't care how the foe gained the condition shaken nor how long the foe would have remained shaken. The dirge ability only checks that foes are shaken and, if they are, then the dirge ability thereafter follows its own rules—until, of course, it can't any longer, like when an affected creature's out of range.

2. A creature that escapes the range of the dirge of doom ability is no longer affected by the dirge of doom ability. If the duration of the creature's demoralization has yet to expire, the creature will become demoralized upon exiting the area. Time spent fightened by the dirge ability, however, counts toward the demoralize effect's duration.

3. To be affected by the dirge of doom ability, "an enemy must be within 30 feet and able to see and hear the bard’s performance," but "[t]he effect persists for as long as the enemy is within [range] and the bard continues the performance." When the enemy who was affected by the dirge ability isn't any longer within range, the dirge of doom effect ceases for that enemy, and that enemy "cannot be affected by it again for 24 hours."

   Thus a bard that's playing spooky music can't just chase after a dude who's already successfully gone beyond the dirge of doom ability's range so as to have the bard's spooky music scare the dude again, despite that chain of events seeming to mesh seamlessly with the adventures of Scooby-doo.

4. The trait Memorable, in part, says, "Whenever you create a fear or mind-affecting effect that imposes a penalty or bonus with a duration of at least 2 rounds, it lasts 1 additional round after it would normally end." While the frightened condition engendered by the benefit of the feat Improved Dirge of Doom does impose a penalty, the supernatural ability dirge of doom itself does not (cf. the spells bane and stage fright that each possess the descriptor fear and that each cause a creature to suffer a penalty directly).

   With this in mind, this GM would err on the side of caution and grant the bard that possesses the Memorable trait no particular advantage for the trait when he uses the ability dirge of doom. However, this GM admits that this ruling may be controversial (q.v. this 2016 Paizo messageboard thread discussing what seems to be an outdated version of the trait Memoriable), so I suggest asking your own GM for a ruling.