Idea for a new throwable.

It would be a gas bomb that explodes upon impact and deals small damage over time to health only, like the storm. It would deal 5 ticks of 5 damage for a total of 25 damage. Caustic would NOT be immune to the effects of the gas bomb as it would contain particles from the ring storm. The smoke effect would last for 5 seconds and be slightly smaller area than caustics gas traps.
It would not disorientate or slow anyone. Only deal damage when you remain in the area of the gas cloud. But if you're hit you cannot escape the 25 damage done.

Pros:

since it only damages health and not shields you can kill people low on health and force people to prioritize healing health over shields.
low damage and quick dissipation of smoke and effects keeps it balanced without devaluing the tacticle effects of Bangalore and caustic.
you can use it to quickly ambush someone at the cost of possibly taking damage yourself if you enter the cloud within the 5 second smoke timer.
can be used to force someone out of a camping position temporarily or into an optimal position to get a shot on them.
you and friendly teammates can be hurt by the bomb so it creates a need for awareness and teamwork ( this might need to not be a thing to prevent teammate abuse, or perhaps if your teammate is hit by it when YOU throw it, you take damage with them, which could prevent abuse a bit)
would be a rare drop with a Max stack of 1, unlike other grenades, so you'll have to be more careful with it's tactical use. Due to taking up one slot it lowers spamming capabilities.
if downed while you still have shield, shield would be used after any knockdown shield is gone, which would make thirsting people harder, and would allow that person to be revived while keeping any shield they had before they were downed.

Cons: