I've seen some inquiries about how the ground DoT works..
The DoT from flamestrike will NOT stack if you repeatedly cast it. You normally get 4 ticks of ~90ish damage if only 1 is cast. If you chain cast twice in a row and stop, you'll get about 6 ticks worth. Meaning: if you chain cast, it'll refresh the DoT duration(overwriting it) but not add a new ground-based DoT. On a differant note, this DoT does work with other mages. 2 flamestrikes can be going at the same time, they just both can't be yours.
In Summary: Ground-based DoTs work the same as normal DoTs.