Armed with the knowledge of the evil plan that Paldemar had revealed to Vadriar, our heroes of the Thunderspire approached the Ordinator Arcanis. He was duly concerned by news that Paldemar might be aggressing on two fronts, but his own hand been forced by Az’Al’Bani’s Gambit and he was committed to defending on one front, whilst ‘the rest of the Mages’ efforts’ were concentrated on defending against arcane assaults — recalibrating the Teleport circles etc. — to deny Paldemar any insider advantage against their defences. They were unable to offer any tangible assistance for a mission to the Sea of Shadows to the site that Vadriar had found being prepared for a ritual a month ago.
But the Ordinator did share with Wjizzo the secret of (the rest of) the command word for the Bronze Warders that are the physical expression of the Mages’ lordship of the Seven-Pillared Hall. In doing so he warned sternly that where two command amulets were both used upon the same Warder, it would open a contest of arcane mastery between the two wielders. (The implication was clear: should Wjizzo try to command one of the Mages’ own Warders, he would be overwhelmed by their superior arcane might.)
And the Ordinator did say that the Mages’ gratitude would run to a reward of an item of magical power just as soon as they could spare someone to create it.*

A show of hands amongst our heroes opted narrowly overruled using the minotaur bullshit-chute, in favour of using the unblocked tunnel from the duergar-stronghold to go down to the Sea of Shadow.
The vast cavern was as Vadriar had described it, feeling vast but strangely muted and echo-less, and containing an underground lake that was wave-less and glassy-still. Everyone felt exposed to possible watchers at any distance away in the darkness, and were glad to retreat until Wjizzo performed his Feylight ritual. Even then they found themselves whispering such that Varris had no need to hush them as he proceeded to lead the way ahead…
Steps led down from the cleared tunnel onto a shore littered with minotaur corpses evidently lying where they had fallen three centuries ago in the civil war that was their downfall. Only the fact that Wjizzo’ and his light kept moving on prevented Vadriar from indulging in an ecstasy of archaeological research. Then they found the recent corpses of four orcs and an ogre on the approach to one of the bridges that projected above the black waters; these worringly bore no sign of the cause of death.
But scarcely had the adventurers stolen forth along the bridge leading into the lee of a great stalagmite — that might shield them from view from as much of the great cavern as possible — when Varris made out several sets chill-glowing eyes hanging in the air to one side of the bridge. Everyone withdrew in good order so as not to fight with their backs to a drop into that fearsome water.
“They’re all around us!” quavered Terrlen at the back, recoiling as he felt a hideous chill close at hand. As the frontal attackers came into the feylight they were revealed as shadowy dark wraiths… But a burst of force from Wjizzo vanquished several of them, and as more came on they were met with arrow shot, eldritch blast and thrown spear and all were felled in turn. (They were suspected to be but the ‘half-strength’ spirits, dragged into unlife by dying at the hands of a true Wraith.) Then a concerted counter-attack attack came from behind. A wave of unholy cold preceded the appearance of three ghostly, twisted apparitions, from which emanated a wave of psychic sickness inflicting illusions of personal horror on any right-minded creature nearby. The combined onslaught of the three spectres literally staggered Terrlen, Vadriar and Cram from their feet, though magical experience gave Elana, Wjizzo and Surina greater will to resist.
Varris at the front was beyond the reach of the attack but surged back with the Orb of Light held before him and drove one of the spectres back out of range of anyone. As he pursued that one, Wjizzo’s magic led the concerted assault of the others against the two, which were promptly cut to ghostly, twisted ribbons. For the continuity-spotters reading on to the next episode, I got carried away here; in fact one of this pair was still on 2 hp…

And one remains. And the master wraith still lurks, just out of sight…

• In game mechanical terms: a 9th level magic item, more potent than anything you’ve acquired so far (with the probable exception of the Rod of Ruin or the Orb of Light in the hands of a fully-approved-of wielder).
  Can you let me know privately (a) what sort of thing you’d most like for your character, and (b) what sort of thing for someone else you think would most benefit the group?