They can't all be winners. After three genuinely excellent side treks, the fourth and final encounter presented in Dungeon #156 is merely average.
The Court of Bones has two interlocking hooks; if the DM is using the Random Encounters from the as-printed module, the players may encounter Az'Al'Bani, a deathlock wight. Az'Al'Bani is searching for the hidden tomb of a minotaur necromancer, and he's managed to discover the sole key that will open its ancient doors.
Az'Al'Bani's not the only one looking for the Court; the drow merchant Gendar is on its trail also, and when players return from the Horned Hold with Urwol's skull scepter Gendar is quick to send them on another quest - this time to break into the Court and recover a valuable crystal which was entombed with its occupants.
As written, the side-trek has players hunting down Az'Al'Bani to obtain the key and then assaulting the Court - or, alternatively, players can just anticlimactically pick the lock. That skips over the various intriguing scenarios involved in bargaining with the wight or even joining forces, but to be fair to author Greg Bilsland it's reasonably clear that those aren't explored for reasons of space rather than any blindness to the idea as a whole.
In any case, when players finally reach the Court they've got a textbook undead battle in store. The minotaur necromancer in whose honour the Court was built is, of course, clinging to unlife, and when players arrive he animates in the form of a lethal Specter. He's attended by a pair of axe-wielding minotaur skeletons and a duo of fireball-throwing undead mages.
It's essentially just a hackfest. If the party doesn't have some divine classes available to totally trivialise these undead, victory still requires nothing more clever than a bunch of damage output and some competent tanking. As is, by now, a Wizards trademark, there's a mosaic in the middle of the floor that provides a trivial regeneration boost to enemies who stand on it.
It's not a bad encounter; it's just not inspiring. It's much like any number of other encounters published both in the retail modules and Dungeon Magazine, and it's probably not worth wasting your players' time on now that the Well of Demons is in sight and we're finally getting to the good parts of Thunderspire.
In short, Thunderspire has more than enough average for go around; we don't need to go to Dungeon Magazine looking for a top-up.