I was recently thinking about how well designed the Oblivion number is, but that it is ill-defined because of the notion of "described in n characters".
My solution is defining it in terms of a formal set theory, such as ZFC. So here I will define Xtrasnack's Oblivion as:
The the largest finite number that can be defined using no more than a kungulus symbols in ZFC.
I am not sure if even this is well defined, so please tell me any suggestions to improve this definition.