Something smaller than an atom. Particles that are smaller than the atom are called subatomic particles. The three main subatomic particles that form the atom are protons, neutrons, and electrons.
Being able to attack on a subatomic level means that a character can use an attack that either reduces their opponent down to their subatomic particles or that it doesn't even leave subatomic particles of the target left.
These abilities can be pretty broken while being underestimated due to their localized nature: even planetbusting attacks may not achieve subatomic splitting.
It is still possible to resist or negate being broken down to less than subatomic particles. For example, extreme levels of molecular attraction, electromagnetic manipulation or reality warping may be able to negate this.
Examples of characters that can attack on a level such of this:
- Characters from Saint Seiya
- The Atom from DC Comics
- Shizuri Mugino and Teitoku Kakine from ToAru
- H-bombs (work by fusing hydrogen nuclei)