I have been running a campaign now for roughly six months (we meet up twice a month). I currently have my party hunting for 5 dwarvish bells to bring a part of a floating city down to collect it the to take the party to it. (These bells hold powerful magic properties as you would expect them to).
So far the party has run two heists: on a drow priestess, and a High eleven family who had the bells.
For the next two bells, I have already thought out where and how they are going to be secured.
I want the last bell to be the source of power for a dwarven mechanical dragon but i am struggling to build a stat block for it. How do I build a mechanical dragon (run by this magical bell) to properly challenge my party? For monsters, I have been using the MM and expansion supplements to fill my encounters where appropriate.
There are seven players in the party, and I expect them to be around 8-9th level by this point. The basic encounter outline is a fight with some smaller constructs and this large mechanical dragon (similar to kobolds and normal dragons).
The fight will be located in the main chamber of a Sunken Dwarven citadel type stricture (like a fantasy rapture).