How about Inundation, just like Incineration, activates at the end of the turn. In other words, it floods (renews) top and bottom floors just like the other would randomly incinerate spaces. It would fix the problem of making Inundation becoming useless after some time. Depending on what type of space it is, it would either flood it or cancel an incineration at that location. This way, they can both work in some sort of harmony as eventually, all middle spaces would be incinerated and top/bottom spaces would either be flooded or just dry. I hope this was clear and helpful.