Guild Wars 2

The above channelled skills (one in pistol main hand, the other elixir gun) seem either to work as one would expect or, quite frequently, to do no damage whatsoever. There is no obvious terrain reason why this should be the case and there is no “obstructed” message, the skills just do no damage at throughout the entirety of their use.

http://youtu.be/aRO-eg_1K64
working as intended.

Fumigate might do no damage if you have no target on skill activation so character fires it into ground (same for flamethrower).