  Generic relevant deformations of Einstein's gravity theory contain additional
degrees of freedom that have a multi-facetted stabilization dynamics on curved
spacetimes. We show that these relevant degrees of freedom are self-protected
against unitarity violations by the formation of classical field lumps that
eventually merge to a new background geometry. The transition is heralded by
the massive decay of the original vacuum and evolves through a strong coupling
regime. This process fits in the recently proposed classicalization mechanism
and extends it further to free field dynamics on curved backgrounds.
