The kids arrive at Bad Guy HQ, where…there’s a crowd of evil shadowhunters just standing around?  Why?  Are they like weird robots who have a standby mode?  Shamble-zombies when there’s nothing to hunt?  What are they doing?

Jace tells Clary to cover her hair because it’s too iconic/recognizable, but Isabelle’s whip and Alec’s bow are left in plain sight.  Brilliant planning there.

A red-clad warrior passed her then, a brown-skinned man, tall and muscular. He paid no attention to them. He appeared to be walking a beat, as were several of the rest of the Endarkened

Guards who don’t react to their environment.  Wow, so useful.

The gates open for them, surprising everyone, even though the whole point of their plan was to be welcomed into the HQ by way of blending in.

They dramatically…cross some empty space and enter a building.  Surprise of all surprises, Jonathan is inside!  Yes, I’m quite shocked that the person they were looking for is indeed in the place where they went looking for him.

Jonathan mocks them for their complete lack of stealth.

“I mean, never mind that obviously I found out from the Queen that you’d come here, but since you’ve arrived, you’ve set an enormous fire, tried to steal a demon-protected artifact—I mean you’ve done everything other than put up an enormous flashing arrow pointing directly to your location.” He sighed. “I’ve always known most of you were terribly stupid.

You know, instead of having a villainous monologue mocking everyone for being so stupid…can’t we just have not-stupid characters?  Can that be a thing?  Because making fun of their dumbassery doesn’t magically make that less annoying, nor does it make the bad guy seem more badass. 

Jonathan carries on with the mocking and talking for a while, and the kids…just stand there and let him, until Alec finally at least tries something.

Alec lifted his bow in a single swift motion. “Foresee this,” he said, and let an arrow fly.

Well he doesn’t really need to when you announce it first, dumbass.

It doesn’t work, of course, because Jonathan is the most magic of the magic people now.

And then demons flood into the place so there can be a big battle. 

What is the point of having all those evil shadowhunters if you’re not going to use them?  You could have just had any random number of them turn and grab while they were walking through the crowd.

While the others all fight demons, Clary runs for a wall and draws a rune portal on it, allowing Jace to go back and get that mysterious weapon that so totally did not help the people who invented it.  Seriously, the people who invented this thing were wiped out, why do you think it’s going to help you?

Oh, why do I bother, we all know the answer is “bad writing.”

Jace comes back with the skeptron, which fights demons by shining some sort of really bright light that basically disintegrates all of them at once.

Why did the last people to have this thing fail again?  Because they very clearly had it once and failed to stop the demon hoard, so…?

Jonathan looks shocked at this utter destruction of his demon army.  Should have had the bad guys standing around outside capture them before they had a chance to do this, asshole.  This is why letting your enemy get right up next to you is generally considered a bad idea.

Jonathan throws a hissy fit over the ruination of his ‘brilliant’ plan, says he’s going to make them pay by killing the prisoners he’s got, and runs off.  They decide to split up to search for him/the prisoners, instead of just figuring he’s probably on the other side of that doorway he literally just ran through.

The room was full of the Endarkened

Oh, hey, you guys are still around.  …and since Clary just keeps running anyway, clearly you are still useless.

Back in our world, Jia stands on a balcony and delivers a stirring pre-battle speech.  It’s short.  …moving on.

Now over to Emma, who is in her room when the “oh shit, we’re under attack” alarms go off.  Emma wants to go off and fight, but Julian deters her by pointing out that he can’t protect the smaller kids all by himself.

I’m not just their older brother. I’m their father, or the closest thing to it

You win the award for creepiest thing ever said by a ten year old.

Clary and Jace run around in the evil HQ until they find a door covered in odd runes.

runes of grieving and sorrow for a world destroyed

Seriously, you need to stop being so fucking poetic; you have lost all semblance of meaning here.

Shadowhunters wore them like badges when someone they loved had died, though they did nothing to ease suffering.

Well then they aren’t really runes, are they?  You introduced those things as being “magic spells handed down by a literal angel,” so if you’re using them as symbolic badges, then they’re not real runes anymore.  Unless runes started out being something else and then a few of them turned magical later?

They go through and find Jonathan in his huge throne room summoning more demons.  Jace then kills it in a paragraph.  Wow, awesome action scene, really.  So useful.

Jonathan banters some more, sends Amatis to go get Jocelyn so he can banter with bite, and then does some magic to keep the two kids from getting close enough to get all stabby on him.  Clary tries to appeal to his ego to keep him calm.

Here I have more than power, Clary. Here in this keep I can shape what is real.”

…and that would be…not power?

Jonathan goes on and on about how awesome it is to be in power and rule over all of hell and be top dog, which is in direct opposition of every other time he’s talked about his motivation in this book, saying that hell is nice and all but it’s just a stepping stone and he wants to burn down our world, too.  Why the switch?  Well…because reasons.

Clary says he can have hell and no one will stop him, but Jonathan wants Clary to stick around, too.  C’mon, he’s only told you that like 23423849832 gazillion times already.  Did you think he’d let you walk off this time?