The aboleth's illusory facade reappears and says "Ah yes, this was well worth the trouble. It will take some time to pour over, but I can already tell there are some real gems in here. The look on your Mistress' face at the end is especially priceless...
Ahem... and now, to keep up my end of the bargain:
The object you seek has not existed for over 650 years. It appears to have disappeared during or shortly after the battle that precipitated the fall of Myth Drannor, and not to have reappeared since then. Whether it was destroyed or not is unknown to me, which is no surprise given its nature.
Even for one as me, knowing exactly what that artifact has done is nearly impossible, as by its very actions it rewrites history and all memories of itself. It is one of the reasons it is so feared and coveted by those who know of it. You can not only defeat your enemy, you can erase all knowledge of his ever having existed, with no possibility of anyone ever trying to undo what you've done. Or so I suppose...
However, all is not lost. There are of course other means to travel through time. If you were to travel back to a point where the object still existed, you could then claim it and travel to whatever time you wanted with it.
Luckily for you, it just so happens that a portal leading backwards in time directly to that final battle still exists. It was erected as a last ditch effort by a powerful archmage defender of the city. With his dying breath, he rent a hole in the fabric of time. It is a one way portal, with the "end" fixed in time and space on the battlefield in the middle of that ancient city just at the time and place where he finished his spell, and then perished.
The "beginning" of the portal has "aged" as normal objects do, so that anyone stepping into it since its creation is transported back to just after the instant it was created. Its creator hoped that even though the invading army of demons was impossibly strong for the current defenders to defeat, that someday the survivors could amass an army (or maybe a small group of champions) powerful enough to go through the portal and ultimately win the battle. Indeed, since then a constant stream of would-be saviors has tried, but of course as history tells us, none of them have succeeded. I would guess that the invaders, being demons, were able to draw upon the infinite numbers of the abyss to replenish their ranks. Indeed, this portal may be why the fall of Myth Drannor was so cataclysmic. The creation of that portal probably led to an enormous influx of numbers on both sides of the battle, with all of them focused on the portal itself, and the resulting release of destructive power weakening the mythals of the city, and likely leading to their collapse.
Of course, much of this last part is speculation, because there are few who witnessed those final moments that still live, and of those even fewer are still sane. Isn't that right, Raoul?
And even if one had witnessed them, since there is a constant influx of people from the future, which presumably changes the past... who knows if one would witness the same battle if they went back and watched it again? Perhaps some among you understand how such things work, but I do not..."