A unique comprehensive, quantitative master model of He-displacement damage interactions and factors controlling their transport, fate and consequences is described. Rate theory is used to track He partitioning to, and recycling between, matrix bubbles and voids, precipitates, dislocations and grain boundaries. Kinetic-thermodynamic data, provided by atomistic scale simulations, is used to parameterize the multiscale master model. Recent improvements include a critical bubble model treatment of the conversion of stably growing bubbles to unstably growing voids, void growth and swelling, and He initially being stored inside the nano-oxides in nanostructured ferritic alloys. The model predicts the combined effects of temperature, dpa, He/dpa, dpa rate and starting microstructure that are consistent with data trends. The more detailed physical model also provides insight for developing simpler, reduced order fit models applied to our large cavity evolution database from both dual Fe<sup>3+</sup> plus He<sup>+</sup> ion-beam and HFIR in situ He injection irradiations.