@A:
Still, the way Caesar talked about the poison, I thought that it encases you and either it was an instakill or at least a short time to kill. When you want a weapon of mass destruction, slow and painful is not really a top priority (unless your some type of Sadist); wiping out as many of the enemy as quick as possible usually takes more precedence , especially if your in a war. Now that I think about it, the toxicity of the gas could propably be adjusted for the situation; such as more toxic for exterminating enemy numbers or less for when you want hostages or just want to take over a place rather than kill everyone.
Well, historically, the best weapons to use have NOT been the ones that kill instantly, unless they are able to kill in truly massive numbers.* It's generally better to wound grievously, but keep the enemy alive, and unable to fight. Landmines blowing off legs, or nerve gas paralyzing the body. This is because it removes the affected from the fighting forces of your enemy, and requires said enemy to devote resources to caring for them, placing a greater strain on their supplies/economy. In this sense, Caeser's gas (an early version of which induced lower paralysis on those who survived) works wonderfully. It will petrify the affected, and hold them in a singular position as it blankets the entire island. Those caught in its effects will be forced to breath in the nerve agent and suffer long term damage to their body. If there are allies nearby, they will be forced to devote time and resources in "saving" the affected, potentially exposing themselves to the gas as well. It also allows the surrounding area to be unaffected, so that if the land is valuable, a small team can move in after a day or two, kill any "survivors" and then immediately make use of the facilities.
It was shown to be very common with both Smiley and Magellan that poisons that don't kill instantly allow enough room for idiots to try and save the afflicted and be poisoned as well.
*And this really only works better as a last resort or when striking against non-military targets. Killing factory workers or the upper echelons of a military/political structure.