Wrath of Ashardalon 'Campaign' - Odd issues

So I'm trying to solo through WoA with a Paladin, I found an interesting problem: what happens if you kill ashardalon while raiding his 'treasure horde' ? Treasure horde was the 2nd chamber/dungeon and Ashardalon turned up almost straight away, I did knock him down to 6HP before tactically withdrawing with the required 2K of loot. But if I had killed him... what then...?

Notes: I've taken out the hidden snipers (loose 1hp if you're not on a tile with another hero as it's auto loose) and added the Blood of Gruumish monsters (since ashardalon has orcs already) Otherwise the game is as standard.

Does it then become a mopping up scenario?

I guess... at then you don't actually need to do the 'slay ashardalon' mission at the end? Just a quirky bug!