And somewhere the author wrote that there are several ways to get to him, but it turns out that I didn't find the wings and it seems like I just arrived by swimming...

Firstly, there are 2 sets of angel wings on the map, but you only need to carry the engraved one.
Secondly, when talking to the dark-skinned character, it is indicated what needs to be done if the wings are not brought - come back to him again.
Thirdly, he will put you in jail - there is a way to escape.
Fourthly, well, there is a way to escape... It's better to stay a little longer, just in case they offer something else. We stay and stay... And the necromancer tricked us.
Fifthly, one of the ways (not to the mausoleum itself, but to its area) is to defeat the "small" stack of dragons, the undead outpost, the gnome outpost, take the astral gate, and the angel wings...
Sixthly, the mausoleum's guards are either defeated head-on (I defeated them like this: mark + crystal + vampire + phantom), or through Andragor (well, you'll have to stay in the dungeon a little longer :) , because every day they offer an escape, and there is also a portal to the city) ;)

and what a surprise the Inferno Castle prepared for me )

If you were Inferno, you would have been given an award.)

It would have been nice to also take the Dungeon castle of the Warlock.

There is a warning sign :) Everyone who didn't make it, let's learn the rules of the road :)
And besides, you can get out of there, even if the castle is captured ;)