  The Cosmic Dawn and Reionization epochs remain a fundamental but challenging
frontier of astrophysics and cosmology. We advocate a large-scale, multi-tracer
approach to develop a comprehensive understanding of the physics that led to
the formation and evolution of the first stars and galaxies. We highlight the
line intensity mapping technique to trace the multi-phase reionization topology
on large scales, and measure reionization history in detail. Besides 21cm, we
advocate for Lya tomography mapping during the epoch of Wouthuysen-Field
coupling as an additional probe of the cosmic dawn era.
