Sorry for derailing the topic, I just wanted to mention that there's also one lesser known way to pull off the dragon cannon.
An Orc Transmuter can do it very effectively too, if a lot of things are present. You can either scum for it (lemmisi helps), or at least keep in mind for the next time you get a good chance for it.
You can generate plants with EM, get up to 100% KB with Binlor, bearmace and a lucky subdungeon, and use GG to turn your attacks into magical. Finding a weytwut will also help in positioning the boss. With 2000 CP (sounds ridicoulous, but reachable) a lvl 10 transmuter would deal 100 damage with each plant. If you save enough CP fodder, well timed conversions can add further damage boosts by spirit swords.
All in all, on a map with lot of plants, with a prepped Binlor and bearmace you just have to find GG and maybe a blacksmith subdungeon for this. It's not surprising that this strat is overlooked, when we think how accessible human transmuters are. Still if you'd like to melee down a boss without touching it, this is a fun thing to try.