Azor: "As caretaker and arbiter of law for the entirety of the Multiverse, it was my duty to collaborate for the greater good. The Immortal Sun was built to imprison one specific enemy. It amplifies the magical abilities of whoever touches it, and it prevents planeswalkers from leaving a plane. The perfect cage for a diabolical Planeswalker! I gave up my spark to help create the Immortal Sun, the lock of my prison, my greatest gift to all living things."
"What evil were you trying to imprison?" Vraska asked.
"A fiend who was a danger to all the Multiverse. Our plan, naturally, was perfect. But my friend failed."
"Our plan? So you made it with someone else?"
Azor growled. "He was my friend. He was supposed to help me get back my spark after our plan worked, which it did not—"
"So your friend helped make the Immortal Sun and then abandoned you?" Vraska clarified, desperate for more information from the slightly batty and clearly bitter sphinx.
"He was to lure our foe to a faraway plane and I was to use the Immortal Sun to enhance my hieromancy and summon that foe here, to Ixalan. But I never received the signal to activate the Immortal Sun. I do not know my associate's fate," Azor said with a flick of his tail. "We devised the plan over a thousand years ago, and I came to Ixalan a little over a hundred years after that. He failed. I do not know what happened, but my execution was perfect—"
Vraska resisted the urge to hurl herself out the nearest window. He's been cooped up on this plane for a thousand years.