They’re here to kill you.

Figures.

Safe bet there aren’t any invisible attackers. They came in pretty loudly.
Casting Detect Magic at them would break her invisibility. She'll just go ahead and guess they've got a lot of magical effects on them, all at relatively low caster levels.
If they're starting a fight, probably they think they can win, and while Orcs aren't known for cleverness she isn't going to just assume they're wrong.

Arkrernux uses her 16 intelligence to see multiple possible futures.
It’s not magic or time travel or anything like that. It’s just thinking ahead. Creatures with 16 intelligence or higher can do that.

What happens if she targets the one who looks like an arcane caster, rushing in invisibly so nobody gets an Attack of Opportunity.

Can she kill him in one round? Nobody else looks like they can see through her invisibility. After that she could survive for one turn, return to the air and become invisible, and dodge them all until their buffs expire.

Great question!

Your bite does 2d8+15 damage, ordinarily. With Greater Vital Strike, it does 8d8 + 15, for a -1 to hit. With Power attack (and your BAB of +17), you can take a -4 to hit for an extra 12 damage.
Expected 63 damage.

Zarhbub probably has 8d6 + 16 ~ 46.5 base HP? He’s got ferocity, so he’s not really dead till he’s at -14. It’d depend on the rolls of the dice.
He can't be an illusion, while the real sorcerer is invisible nearby. You'd notice on Blindsense. He might have False Life, or Bear's Endurance, or Mage Armor, or Stoneskin?

It’s a gamble.

And then I step on top of her and Full Attack, taking out most of her HP in a single round.

Fucking what? How?

I have a lot of numbers that add on top of my already pretty big numbers to make the numbers get even bigger.

What happens if she delays her turn until the flying guy wanders into range looking for her? That way she'd get to Full Attack first.

You can’t kill me with a full attack in one turn, if that’s what you’re thinking.

And you’ll lose your invisibility, and then we can make ranged attacks too.

You want to fight me?

COME AND GET ME.

Fuck.

What happens if I open with my fire breath?

If we’re coming here at all we obviously know you’re a red dragon.

Protection from Energy is only third circle, and at level 8 it covers all of us for up to 96 points of damage.

12d10 fire damage is, on average, 66 damage. You won’t overwhelm the Protection in one round, and next round you won’t have your invisibility and they'll counterattack.

It's not a gamble, to do that. It's just suicide.

Why are orcs like this? Still, they’re underestimating 16 intelligence, because every orc does.

Her best bet is: Dispel Magic, on the Fly spell.

Because then she can immediately fly away.
She doesn't need to check. It's obviously a fly spell.
Orcs aren't known for their strong ranged attacks. She's pretty sure she can make it alive if their leader can't get into melee.

1d20 + 7 = 26.
Trahk Mul falls to the ground.
Trahk Mul takes 3d6 = 11 fall damage.

Also, Arkrernux is no longer invisible.

Excuse me, mother?

I just got back from the secret secondary escape tunnel.
There’s a group of rather angry looking green men there.
Also, the tunnel was blocked off by a wall of stone that wasn’t there yesterday.

I suspect some kind of magic may have been used.

... Fuck.

Okay don't worry she can totally still get them out of this. They just need to work together.

It's starting to feel like obeying this suggestion is obviously harmful.

Could I maybe not?

Fine, but only if it's really obvious that sitting still and being quiet will kill you.

Mother, we’re being attacked! What should we do?

They can see me now, right?

Frightful Presence (DC 21).

Trahk Mul: 1d20 - 1 (Wisdom) + 4 (Barbarian) + 2 (Iron Will) + 5 (Superstition) + 2 (Resistance) = 22. Passes.
Ladakh: 1d20 + 3 (Wisdom) + 6 (Cleric) + 2 (Iron Will) + 2 (Resistance) = 22. Passes.

A lot of the others are going to be Shaken by it, and they might not respond well to that:

Orcs are bullies and cowards. They flee when the odds have turned against them and any nearby leaders are dead— or have already fled. 

A frightened creature flees from the source of its fear as best it can. If unable to flee, it may fight.

Ladakh has a confession to make. She would like to get something off her chest.

Earlier, she Stone-Shaped the entrance to this cave closed, leaving only a small gap that an orc would need to squeeze through to get back out.
But she told everyone she was going to lock it up completely closed, and that she had an extra slot with which to undo it later.

She used an advanced Lamastan technique called Lying. Anticipating fear effects might come into play, she preferred it if all her allies believed escape was impossible, and their only hope was to win, or at least to keep her alive during the retreat.

She did not actually have a spare slot going free though, and she didn't want to be stuck here until tomorrow, so she didn't actually shape it totally closed.
Everybody just kind of rushed in without looking back.

In other words, you can scare these idiots as much as you want. None of them are running anyway. None of them realise they can.

Okay kids, the next part of my plan is a bit complicated. Please try to follow my exact words.

You know how we keep piles of dried wood around the cave for no obvious reason? I need you both to ignite some with your fire breath, and scatter them around.

I can cast Pyrotechnics at will if I've got fires to target, and fill the room with smoke they can't see through but I can. Since it's not targetting the attackers, I can recast and keep up invisibility, so I can stay alive until they're all buried in smoke. That should buy us enough time to either smash down their wall and escape, or else burn them while hiding in the air where they can't get us back, or else wait out their buffs and suffocate them all to death.

Weren't you going to kick us out of the nest a few minutes ago?

Dergaix wasn't listening to Ladakh back then.
He's still 70% that they only blocked the back door and if he rushes past he might escape.

I suggest you help with my plan. For your sake.