Not-so-skinny dipping

Leaving the ziggurat, we decided to have a quick look at the moat and see what was around the corners of the ziggurat in case we were missing something interesting. In retrospect, this was possibly a mistake because the chap on the wyvern perched on top of the ziggurat, who we has completely forgotten about, decided to come and check us out. He landed on one of the pillars on the bridge, which in retrospect was a mistake for him. Our attempts to talk our way out of trouble failed miserably (as normal), so we attacked him before he could attack up. I think the illusion of Windvane as a flagpole was particularly suspicious. Thorg used his Ring of the Ram to shove the wyvern off the pillar, which meant it was busy frantically flapping to maintain its balance as we started hacking at it. I almost came a cropper forgetting that the tail end of a wyvern is more dangerous than the teeth end, but had a lucky escape. The dying wyvern and rider toppled into the moat, so I used my Driftglobe to illuminate the depths. There was not much on their bodies, but quite a bit of stuff littering the bottom of the moat, which I started scooping out with a Mage Hand. We saw why this was when a giant dwarf golem came trundling around the corner, but fortunately it ignored our magical delvings. The real coup came on the far side, where we found a well preserved set of Dwarven plate mail, which Thorg immediately grabbed and started cleaning up. The clanking has gotten worse.
That finished, we returned to the courtyard with the fountain looking for Windharrow, but he was out. Proceeding around the temple compound, we found one room with several initiates whipping cultists into turning some huge shafts running from floor to ceiling. In a room next door, we found a group of prisoners being guarded by some Kenku, so we killed them (the Kenku) and released the prisoners. We didn’t try it the other way round – I don’t think it would have worked as well.
We now crossed back to the northern side of the moat, to find a plaza and some dwarven shops – long abandoned. One proved not to be abandoned though whne Thorg was attacked by a cloaker that dropped on him from the ceiling. We were now feeling pretty beaten up, so camped down for a long rest to recover in one of the cleared out shops. When we continued, we found a large dwarven tavern that showed signs of having been recently occupied by cultists, and swiftly and recently abandoned. We assume that unfortunately the rest of the air cultists have fled. We did find some more Kenku though, who tried to run away. I stopped the exit with a Web spell, and we killed them, although the fight proved to be a particularly long one, and we took a fair bit of damage. We explored the deserted ruins further, finding a temple of Moradin whose doors had been spiked shut from this side. Suspecting undead, we didn’t open them. Just beyond this, though, we encountered an Umber Hulk, which managed to bemuse all of us apart from Storm. We though we were goners, but managed to pull it back and play tag-team with it to avoid its gaze.
By now we were once again bruised and battered and our supplies were running low, so we decided to pull back to Feathergale Spire, and possibly enter the dwarven city from one of the other cult temples.