In general relativity producing a regular bounce entails violation of Null Energy Condition for a dynamical source in the model.
That generically indicates existence of ghosts or other instabilities.
However, in cuscuton modification of gravity, the correspondence between a background bounce and violation of Null Energy Condition for dynamical sources is broken.
Cuscuton action, modifies equations of motion in Infra Red limit allowing the background to go through a regular bounce phase.
At the same time, since it does not contain any dynamical degrees of freedom, it does not lead to ghosts or other instabilities.
Here, I present a toy scenario of a regular bouncing cosmology and prove this claim