Since Jorb has stated that these are "planned" at some point, and haven desperately needs an endgame that isn't just killing people and/or watching the numbers go up, or making larp towers, here are some ideas
Non-combat:
1. Dragons should spawn very rarely, on mountains or outside caves.
2. Offering gold to the dragon should give some sort of boon, like a bonus to learning ability (I know, not in the game, but neither are dragons, lol)
3. Dragons should occasionally carry off livestock from nearby villages (once per RL week, unless you feed it some wild animals possibly)
Combat:
1. Attacking a dragon requires you to be in a village and have a character with at least 1 million LP and 50 intelligence. Otherwise it will just kill you instantly when you attack it, and ignore your puny settlement.
2. Meeting those requirements means the dragon takes off, and starts to path slowly towards your village, if it is not directly under attack (i.e., once it kills you all). It takes ~8 RL hours to get there, depending on distance, randomly burning stuff down on the way (trees, noob settlements, etc).
3. The first stage of the fight the dragon is in the air, and thus can only be attacked with bows. The dragon attacks occasionally with slow-moving fireballs* that just kill you, sorry**.
4. After you deal a certain amount of damage, the dragon falls from the sky and starts biting and clawing you all to death, as well as launching the fireballs. However they dont move that fast when they are on the ground, so you may be able to kite them. In this mode, the dragon has a lot more AC, since the soft underbelly is not exposed. So arrows won't really do much.
5. If the dragon kills you all and is no longer in combat, it continues on towards your village, breaks in and burns down your houses. Sorry. At least the kilns are alright, it likes stuff that burns other stuff. It squats on your idol someone kills it, and attacks anyone that moves within a certain radius
6. If you kill the dragon, you get dragon hide, teeth, skull, dragon meat, and some gold.
*This may be hard, since it is essentially an object spawning an object, which doesn't happen much in haven (cows giving birth as an exception?). It should! Also with support for this then we could have actual projectiles for spears and arrows instead of the current laser beams
**The idea is that it is gated by player skill rather than stats