He forced his degenerating body into a submissive posture, arms wide, palms open.

"Well, you've caught me out."

It was a calculated risk with a variety of possible outcomes and only some of them Final. Final was something the Master wanted to avoid at all costs.
"You will be Exterminated." The flat metallic voice should not have been able to convey pleasure, but delight was evident, perhaps in some subtlety of timing.
"There is a prize offered for my capture." The Master baited his hook carefully. "By the Time Lords of Gallifrey." He cast it with practiced skill across the waters of vengeance and greed.
"You've heard of them? Or one of them, perhaps - the Doctor?" A brief pause while the Daleks communicated with one another and their superiors. Would they take the bait?
"You will come with us. Obey or be Exterminated."

Obedience was a part of The Plan.
A Plan dependent on a faltering foundation of uncertainties that made sense only in the face of the fact that in his current form, the Master could not survive eternity (or any reasonable portion thereof) intact. The Master knew he was no longer fully able to judge the comparative competence of this project. Painful, aching, fleshy decay, forcing a nearly constant search for the next, fresher vessel to carry his animating essence was working against him. He had a niggling suspicion that bits and pieces of his memory and intellect were falling off when he transferred from container to container, lost perhaps during the deterioration that began as soon as the original inhabitant was evicted. There had been a technique to slow the process, he remembered that much, but could not recall the specifics. No sense pursuing it, survival depended on utilizing what was currently available.

Item: The techniques that preserve the essence of sentient animation fail only if the essence is trapped inside a vessel when it is destroyed.

Item: The Daleks are driven by greed for control which means they can be led by promises of power.

Item: Even the Time Lords want to stop the Master. Jealousy perhaps, or cowardice, the Master reasoned, but sufficient that the rulers of Gallifrey would pay well to be certain that he was no longer a threat to the Established Procedures.

Item: The Daleks hate the Doctor, instrument of the Time Lords, and fear him.

There were mercifully few secondary Daleks to deal with before the Master was presented to a Prime Dalek, one to be reckoned with, one to strike bargains.
"We know of you, Time Lord. Stealing the bodies of our rightful slaves is not the only crime you have committed."
The Master nodded in agreement. Progressive wasting of the stolen body inflicted its own uncomfortable punishment with every movement; he had a day, possibly, to make this work.
"Have you contacted Gallifrey yet?" No sense wasting time on dangerous preliminary conversation.
"For what reason?"
"The reward, of course! Surely you've heard of it?" The Master was uncertain which approach would be most effective with Daleks. It was difficult to determine how much they understood.
"We hear only that you are a Renegade and a criminal." The mechanical voice grated out each word without intonation and yet contempt was clear. "Where is the gain in offering a reward for what is useless?"
"The gain is yours for claiming it." The Master tried one more time to assert his usual variety of mental control on the Dalek. In most beings, he felt this in his own mind like grabbing a handful of clay, soft and ready to form. With Daleks, it was like grabbing air - there was no turning their attention, no apparent way to hypnotize them, no evidence that there was any mind at all.
"What is offered?" Each buzzing syllable expressed interested greed. Even without a telepathic connection, the Master knew that all top ranking Daleks were in electronic attendance at this interview.
"The Time Lords might be open to requests. They place a high value on the remains of their own. Even outcasts like myself." The Prime Dalek turned and left without another word. Since there was no place to sit, the Master remained standing, outlining his plans, listing and reassessing resources, keeping his intellect busy while the borrowed body dropped fur in shaggy itching patches.
When the Daleks returned, the Master was shaking with fatigue. "
The Time Lords have agreed to our demands." A Prime Dalek was followed by two drones. "They have offered this urn for your remains." The second drone bore a carryall holding a traditional Gallifreyan funeral urn. The sight of it made the Master smile grimly.
"The Doctor will be sent to exchange the Secret of Time for the urn after you have been Exterminated." Perhaps it was just the sound of the word that gave the impression that Daleks relished the thought.
"The Doctor?" Here was an opening door, possibilities previously unconsidered. The Doctor's capacity for kindness left him vulnerable.
"We requested it in your name." The monotone glinted with smug satisfaction.
"Ah! And when the Doctor arrives, you will eliminate him after he delivers his part of the bargain." The Master managed another smile, but loss of muscle tone made it lopsided. "A very clever conceit!" A mere click of his heels and slight formal bow pulled the ligaments in his lower back from their moorings. By the Heir of Rassilon, the pain of this subterfuge was almost unendurable! But the rewards! The rewards! The Doctor's TARDIS, perhaps even the Doctor's lives...
"Leave me alone for a few moments with the urn, to contemplate my end."
"We shall return to Exterminate you."
The Daleks withdrew, leaving the urn behind.
Given sufficient practice, an adept can achieve with ease even the most difficult feats. So it was with the Master, as he slid his essence into the iridium lined bowl of the urn, leaving behind only a small residue to control the rotting hulk that had carried him for the past three days.
Charges were read when the Daleks returned, and the Extermination proceeded satisfactorily for all involved.

When the TARDIS arrived, more or less on schedule and just about where it was expected to be, the doors popped open and the Doctor's voice was heard.
"Please come in. The ransom you requested is just inside the door. If you will place the urn beside it before you leave, I would be obliged."
A Prime Dalek pushed past the TARDIS doors and rolled over the threshold. A pair of drones with a carryall containing the Master's urn followed behind.
"Where is the Doctor." Irritation was evident in the flat vocal buzz. "We must see the Doctor."
"Of course." The Doctor's Seventh self stepped from behind the console. "A bargain is a bargain."
Two more drones appeared in the TARDIS door and moved to the sides until their forward motion was limited by a short descent of steps.
"Exterminate! Exterminate!"
"Exterminate! Exterminate!"
There was a brief confusion of futile clicking and frustrated Dalek commands.
"Exterminate! Exterminate!"
"Your energy weapons won't work within the TARDIS, I'm afraid. A damping field, you see. Terribly dangerous to let bolts and projectiles fly about inside an instrument as delicate as this." Placing the urn on the floor beside a seamless rectangular chest, the first two drones hooked onto straps around the sides and began to drag it out.
"Stop!" The Prime Dalek had been inspecting the object with its eye stalk. "There is no opening."
At this, the stuttering drones ceased their attempts to Exterminate the Doctor and turned toward the strapped chest. "How do we know it contains the Secret of Time?" The Prime Dalek's voice rasped with suspicion. "How does it open?"
"You know it contains the Secret of Time because it came from the Time Lords, who agreed to your outrageous price, and I have delivered it as requested." The Doctor stepped forward to mount the steps. "It will open for you when you have achieved the learning necessary to use it wisely."
He stooped to lift the urn with care.
"The door is behind you, and thank you for your consideration." With that, the Doctor retreated down the stairs and disappeared into the shadowed depths of the TARDIS. Unable the follow, the Daleks took their box containing the Secret of Time and returned through the doors to Skaro. They had plots to hatch.

There was some satisfaction for the Doctor when he sealed the urn into a magnetically bound coffer, but he was uneasy none the less...

"Even in death, I could not trust the Master."