Novel collective phenomena are being revealed under various extreme conditions, which are challenging the current theories and have attracted broad interests over the community. In this talk, I will present observations of exotic behavior emerging in correlated materials by applying either high pressure or high magnetic field. Attentions will be paid to the unconventional superconductivity appearing on the edge of antiferromagnetism and valence instability in heavy fermion metals while tuning their electronic interactions via pressure. The fate of f-electrons at a quantum critical point will be discussed based on the measurements of dHvA effect. The unusual physical properties of the iron pnictides in extremely high magnetic fields will be shown and compared to other layered superconductors. Emphasis will be putted on our recent observations of nearly isotropic upper critical field, the extreme robustness of the magnetic order against magnetic field and the unique Hall resistivity, which indicate the importance of electronic duality in iron pnictides.