Storm King's Thunder #29: Heavy Lifting in the Battle of Ascore

TL DR  Ultimate battle?  In the midst of the heroes battling gargoyles above the sands of the Anaurach Desert, it was proposed that initiative be decided based on contests of strength between me the DM and various players (we usually use side initiative on a d12).  I won the first push up contest(22), then lost the second(31),  then lost a pull-up contest(7), and finally outlasted my wife in a side-plank contest.  Hilarity ensued.  Yes a bottle of wine was involved.

DM Notes
The end is nigh.  I can almost taste it.  And I don't mean the imminent return of Tiamat.  I mean the campaign itself.  With this last battle against the Blue Menace of the Anaurach I plan to hand over the reins to a friend and retire from DMing type V D&D.  I hope it feels satisfying enough for the group, but I'd like to pause it for awhile and pick it back up on an episodic basis, roleplaying a scene here and there before another epic battle with the queen of dragons.  At this level plot points seem sort of inevitable and less surprising, at least for me.  I'd like to make the playing through of those plot points special occasions instead of weekly affairs.  I'd never really agreed with the term "to play through" a module until things got to around the 10th level, when astute players can more or less make things happen as they like.  I'm looking forward to being surprised by the game again, this time as a player in Tomb of Annihilation!

In the meantime, I'm hoping to make this battle one to remember.  They've already taken down a couple dragons during this campaign.  This time they've already had their plans shifted by terrain and spells drained by multitudes of minions.  I hope to make it a running battle in a cyclopean min-dungeon, with mysteries and traps along with their ultimate foe.  I won't say I want to kill some characters, but if one or two die it wouldn't make the campaign less dramatic.

The Story
The Red Balloon arrived in Silverymoon to great fanfare.  The glitterati of the city turned out to celebrate the heroes of the realm, who had walked the very halls of the Maelstrom Court and not only lived but returned as friends and allies of the Storm King himself!  They were invited to many balls, feasts, and theatrical performances, their deeds were turned to song, and all the kind help of a grateful kingdom was opened to them.  For a time, all was well, but the doom of the Drakkorn still echoed in the hearts of the mighty and though giant kind had ceased their destructive depredations, dragons continued to sail out of the northern reaches, headed for some southern clime.  A migration? or a meeting?

Feeling there was little time to waste, the Red Ballon set forth once again, now crewed by hearty men with curly beards, into the oncoming storm of the desert.  From the ancient ruined city of Ascore could be seen a violent thunder storm swirling above the great amphitheater said to crown the lair of the ancient sapphire wyrm to whose credit was due the manifold sufferings of the Forgotten Realms these many months.  The crew landed the Red Balloon and approached under the influence of magical spells of Flight, cruising low.  Even so, heavy stones, fragments of statuary were launched at their approach by vigilant gargoyles, one catching the cleric Apollo on the shoulder blade, sending him crashing into the sand. 

Althea the Wizardess and Ezra the Storm Sorceress summoned fire and ice to shatter the guardians, and Ezra sensed a great malevolent presence guiding the storm above.

Circling about, chased by dozens of stoney, bat winged devil statues, the heroes dove into a great hole in the ground within the amphitheater, finding themselves in a massive vaulted underground chamber.  Gargoyles screeched above.  A massive presence filled the space.  They were not welcome here...