It can seemingly be any element, and some models shoot 2 bullets at once, and others have scopes. It can also come with an attached blade to increase melee damage.
This gun also has two main types cold and vile in which vile has a lower fire rate, accuracy, and power than the cold. There is also a "Double Thanatos," which shoots 2 or more bullets per shot, a "Stabilized Thanatos," which has higher accuracy and lower recoil, and a "Fanged Thanatos" with +100% melee damage. There are also types for each element with varying elemental power (x1,x2, and maybe x3 or x4, not confirmed yet though). There is also the "Scoped Thantos" just referring that it has a scope.
The Thanatos accessory which gives this weapon its name is glitched and causes the weapon to have the Pearlescent rarity.
Big Tony is a common name for a mobster, and the increased magazine reflects the "Tommy guns" used by mobsters in the '30s, due to their large "Drum" magazines.
Thanatos is the personification of death in Greek mythology.
Most commonly found in vending machines.
Due to a patch that was recently released the Pearlescent status of this weapon has been removed, it is now any shade of orange.