"In the last thirty days, how many corpses did you witness being brought to the morgue and prepared in the manner I observed?"

"Twenty-six."

How many in the last six months?

"189. And a half"

"Explain."

"Gate man paid full for a corpse that was missing its legs.  And a good portion of the pelvis.  Ghoul feeding, I guess. 

"He got sacked."

"How many did you witness in the last three years?"

"Seven hundred sixty-eight."

"How many in the last two years?"

"Six hundred ninety-four"

"How many in the last thirty months?"

"Seven hundred sixty-eight."

"Where were you on this day of the month thirty-one months ago?"

"I couldn't tell you."

"Provide a list of things your binding prevents you from saying."

"I am not able to answer that.  Cut it out, will you?"

"Who is Pharod?"

"Not a key that opens any locks for me, chief.  Sorry."

“In all you’ve read and encountered, what are some creatures that are either known to dwell in the shadows or who excel at tracking their prey.”

"Let's see.  For starters, running through the Planar Parade A to Z...

• The Athar are skilled assassins and spies that are known to strike wizards from the darkness, nullifying their magic
• Cranium Rats keep to the shadows in the way that any vermin does, and they’re everywhere in Sigil, and enough of them might make an intelligence large enough to be a threat
• Darkweavers are giant venomous spiders supposedly from Shadowfell, and they always wait in positions of total darkness. You’re supposed to hit them with fire and light, in case you were wondering
• Mercykiller bloodhounds are humans trained to track prey across the planes. If something is tracking and hunting you, maybe they’re a good fit
• Trelons are big black beatles from one of the lower planes. Kind of like cranium rats, but stronger and stupider. Also, they don’t have the mind meld thing going on
• Vargouilles are little batlike things that are known to swarm in the Undersigil"

“My tattoo said ‘beware the shadows’ and ‘can hunt you reliably’ or some such, yes?

Taking that as the criteria... that would suggest... what? Either Athar or Mercykillers?  

You said you believed my body was likely picked up in an alleyway or a nearby gutter. Which of the creatures in your list are most likely to have been in Sigil and incapacitated me?”

“Hmmm.

The Athar were driven out of Sigil by the Harmonium quite a few decades ago.  They do have a ruined guild hall in D’Angles a few miles from here, but it’s nothing but a burned out hull.  No roof even, when I saw it.  Mercykillers in Sigil are mostly working the prison in Lady’s Ward.  That’s the faction name.  It’s only a tiny number of them that are trained bloodhounds, though, and neither Athar nor Mercykillers are exactly regular to see walking about the streets of Sigil.  Granted, if they are minions of something greater, maybe they could have arrived here to attack you.  I don’t see any of the others I listed, realistically.  Darkweavers are stationary.  They don’t hunt.”

“And how likely do you think it I was ambushed by Athars or Mercykillers? Greater or less than a coin flip?"

“Wouldn’t take any bets on it.”

He turns his head back and forth brusquely, calling to mind a horse shaking its mane.

“You asked.”

He nods. 

“I agree with you. The chief difficulty I see is that it doesn’t make the slightest bit of sense.

Consider. I am an immortal. I perceive the threat of becoming an amnesiac. I take the precaution of tattooing instructions upon my own person and of keeping a locked journal to bring me up to speed after the fact. I know at least something about the enemy that is pursuing me. Presumably I have taken other countermeasures against being ambushed.

Then, I am surprised and defeated, and I awaken not in a jail cell, but within a very weakly defended basement, stripped of my journal and abandoned by any allies I might have had, but in no other way inconvenienced.

If I were faced with an unkillable adversary, I can think of a few obvious things to try…"

He trails off, declining to state aloud for Morte how he'd have attacked an immortal.

Bury them alive. Plane Shift them to somewhere inhospitable. Lock them in irons and drop them in Carceri. Alternatively, use a non-violent approach. Recruit them. Bribe them. Mislead them into serving your interests. Mind control them. Explore vectors to permanently damage their mind so they could never be a threat again.