so the 1st level "Obscuring Mist" spell stops ALL channeling.
A misty vapor arises around you. It is stationary once created. The vapor obscures all sight, including darkvision, beyond 5 feet. A creature 5 feet away has concealment (attacks have a 20% miss chance). Creatures farther away have total concealment
So your 10 feet away and that 20th level evil cleric that just channeled a can off whup-a*s dos an epic fail with a 1st level spell.
No. Read that again. Obscuring mist provides total concealment. Not the same as total cover.