Although weather is a long-standing threat to PC parties, the tornado is unique. Heat, cold and rain are just parts of the environment. No sense fighting them or avoiding them, since they are literally everywhere. A tornado is different, a serpentine ribbon of death meandering across the landscape. In order to kill it needs to devour you. Sounds like a quality monster to me.
In my module, “Tree of Shadows” I made the first encounter a tornado. I thought it was better than the usual “OTA” (Obligatory Thug Attack.) Some new mechanics were required to deal with this unusual beast, but I think it worked out well.
The setup is that the party was escorting a group of monks when the tornado struck. Several monks were thrown into the twister’s path, unconscious. The PCs, being PCs decided to rush in and rescue the injured.
I labeled our battle map with vertical and horizontal axis, numbered 1 to 20. Due to debris and poor visiblity, half movement is the maximum inside the grid. Outside the grid is only 1/4 movement. This discouraged the PCs from going “off grid” to avoid my lovely tornado.
I spread some victims out in the grid and the PCs went in to rescue them. Every round I randomly rolled 2xd20 to determine the vertical and horizontal location of the tornado for that round. Just to make it really interesting, it had reach 10. A near miss, inside the “reach” allowed for a fortitude save. Failure meant the tornado ate the PC for 1d6 rounds until spitting them out in a random direction. I applied damage every round to the PC while in the funnel. It if landed on the square with a PC in it there was no save. It is a tornado, after all.
I have to relay this humorous gaming anecdote. One of my playtest groups had a mount (a war horse) picked up in the first round. A few rounds later it was ejected, landing on a random square…occupied by its original rider!
The encounter ends after 10 rounds or when all the victims are rescued.
I have more detailed instructions and graphics in my module, linked above for those needing more information.
Just another encounter suggestion from my dark and twisted mind.
Trask, The Last Tyromancer