Dragons in Monarch will not be common occurrences. We want to make the dragons in our game as mysterious as they are powerful, so you won't just be happening across a dragon every day while your castle or Kingdom's countryside is being raided; however, we do want to make sure we keep things balanced!
While dragons will most definitely be powerful and cause a lot of damage, shifting the tide in a siege will come at a dangerous cost. Dragons won't respawn when they die, and large ballista could be a problem for dragons, but none the less, a single dragon could possibly lay waste to an entire castle's keep whether you're riding on it's back, or commanding it from the ground.
@Laurathechic This sounds very interesting! Our dragons in Monarch will most definitely be capable of magic-based abilities too. We were thinking mechanics along the lines of having dragons take on the personality of their bounded players, so this fits in perfectly!