Too bad any grounded pokémon will not get burned by Scald.
Also, as long as Misty Terrain is up, this thing cannot even use Rest.
It might be better off with Surf or Hydro Pump considering Misty Terrain won't let opposing mons get burned.
All of the time Misty Terrain being discussed, all posts tell that Scald can't burn in Misty Terrain, so nor will Discharge do.
Replay of it
In this replay, when Misty Terrain was active until Turn 8, Scald didn't burn opposing Blissey. However, after it disappearing, Scald burned Blissey on Turn 15.
Well it was bit of my unluck that it took 7 Scald after Misty Terrain to burn, but regardless Scald can't burn, nor Discharge to grounded Pokemon in Misty Terrain.
Hope this helps!