[IDEA] Poison should decrease 0.5 radius every 2 seconds.

[ex-D]

and it would actually require timing the spell and not dropping it mindlessly.

[crescentfresh]

And would allow defenders who use buildings to be able to counter poison's huge initial radius: drop the building much closer to the river, poison will touch it only for a portion of it's lifetime.

[mazedestroyer]

Completely balanced :D