How about the second door to the right, does it have any objection to being battered down with a nonconductive heavy thing?
Acid's easier to dodge. And more likely to inconvenience any pursuers afterward. He keeps swinging. If this door can be broken by force, it will break soon.
That was to be expected. But if the magically sealed and acid-trapped door wasn't made immune to battering rams, the wall probably wasn't either. He turns left and tries bashing his way through.
The room Promise recommended is unoccupied, full of musical instruments, and possessed of the commodity of a balcony. From it, he can see the balcony to the Queenly bedroom. He cannot see the gate, because that is not how gates work.
On this balcony there lands a silver-skinned blue-eyed fairy...
"Cease," she commands sternly.
"No," he meets her eyes, "You stop."
While Alendi's looking over to see whether the smaller fairy's wibbling has intensified, he meets with yet another blunt impact.
He peels himself off the floor and directs the Queen, "Don't let anyone interfere with me." Then he rushes to grab her and jump for the gate.
And he's back in Scadrial, and Promise closes the gate and stares at the queen and trembles. (Yellow covers his eyes and squeaks.)
"I've told her to stop," Alendi says on the off chance that Promise isn't deaf right now, and gestures in case she is. "I...haven't really thought about what orders happen now."
"Can you hear?" she asks Alendi. "Make her forget my name, see if it works."
"Store Promise's name in this piece of copper," he says, holding an unused ring against her hand. "Nod when you've figured out how and done it."
For future reference, never lie to either of us."
The queen cannot answer, because that was not an order or a permission.
"Tell me whether you know her name."
He returns the spike to it previous position. "If I sent you to collect a certain fairy who has irked me, one who has defenses sufficient to capture unprepared intruders, how likely would you be to be succeed?
Answer any question we ask you."
"Let her breathe," Promise says. "Snap your fingers if she knows my name."
"You can breathe.
Who fed me while I was captured?"
"Tell her never to give me orders and snap your fingers when you've done it," Promise says.
"Do not give Promise any orders," he snaps his fingers again. "Or Yellow. And if you ever happen to see Nighteyes or Spellwhip, make them never give me any orders or attempt to get out of that order."
"That's Yellow, this is Alendi," Promise adds helpfully, pointing them out. "Alendi, this will go faster if I can command her too; if I send Yellow out of the room will you make her state her name?"