Ahh you mean Volcano.
It would be pretty much impossible to make a "real" volcano in UO though you can make one that sort of tricks the player into thinking that they are on one.
First volcanos are huge and if they are pumping lava then the lava gets denser as you get to the center so you can make none spiraling paths to the center. Elevation really doesn?t need to be that much of a change to create the effect, perhaps even less that 40z in height.
Volcanos would be a combination of dirt, lava and mountain terrain with a splash of grass or other terrain at the base. If you prefer to make it mountainous then you can do so but keep the terrain low so it?s easy to see the whole effect. If you get to steep then it will just look like a mountain with lava puddles on it.
As long as it looks like a volcano on the players radar map then they will get the overall effect. Try small streams of lava flowing between little puddles or lakes. You can draw dirt paths to connect it all while edging the lava with rock terrain. This will get you a spider web looking effect which should work perfect.
You can also pile rock tiles up with dirt paths going across to create the effect of a natural bridge, use the no draw tiles around the dirt to edge it off where ever you want to make a crossing on your map then fill the lava in by hand later.
The edge created by Dragon for lava looks like black swamp crust which is ok in moderation but normally generates far too much of it so I would recommend removing that effect and placing the crust in patches later.
Don?t forget to place loose rocks around or in the lava flows, this enhances the effect of destruction. Small campfire, brazier and torch animations placed in rock formations or on the lava pools their self also enhance the effect.
Perhaps a village was nearby and destroyed by the lava flow creating an effect like the Chaos shrine in Ilshenar. Perhaps there is an evil orc fortress within the winding flows.
You can go one step further by placing a savage village nearby with a nice virgin staked out for barbecuing later.
There is no limit!
Dev