  The explosive transition of a massive neutron star to a quark star (the
Quark-Nova, QN) releases in excess of ~ 10^52 erg in kinetic energy which can
drastically impact the surrounding environment of the QN. A QN is triggered
when a neutron star gains enough mass to reach the critical value for quark
deconfinement to happen in the core. In binaries, a neutron star has access to
mass reservoirs (e.g. accretion from a companion or from a Common Envelope,
CE). We explain observed light-curves of hydrogen-poor superluminous Supernovae
(SLSNe Ia) in the context of a QN occurring in the second CE phase of a massive
binary. In particular this model gives good fits to light-curves of SLSNe with
double-humped light-curves. Our model suggests the QN as a mechanism for CE
ejection and that they be taken into account during binary evolution. In a
short period binary with a white dwarf companion, the neutron star can quickly
grow in mass and experience a QN event. Part of the QN ejecta collides with the
white dwarf, shocking, compressing, and heating it to driving a thermonuclear
runaway producing a SN Ia impostor (a QN-Ia). Unlike "normal" Type Ia
supernovae where no compact remnant is formed, a QN-Ia produces a quark star
undergoing rapid spin-down providing additional power along with the 56Ni decay
energy. Type Ia SNe are used as standard candles and contamination of this data
by QNe-Ia can infer an incorrect cosmology.
