I wonder about 'toxic rain' can has critical chance when dealing DOT chaos damage.

and wonder toxic rain is 'Aliments" and can apply 'Perfect Agony', 'Dire Torment'
If someone let know these questions then it is very helpful to me and thanks to you.

Toxic Rain is not an "Ailement".

https://pathofexile.gamepedia.com/Toxic_Rain

The Arrows and the Explosion of the Pods can inflict "on hit effects" such as posion (which is an ailement) but the Degen from the pods is not a hit and not an ailement.

Perfect Agony/Dire Torment would help for poisons applied by the Arrow and Pod-Explosions but not for the Degen.

Hope that helps.