Lyman-alpha blobs are mysterious gas clouds in the distant Universe that extend to tens or even hundreds of kpc. Our team, including astronomers and engineers at SNU and KASI, is conducting multi-wavelength, deep, and large area surveys to identify and study tens of blobs at redshifts 2-5. We show that blobs occupy massive halos likely to evolve into rich groups and clusters of galaxies today. As such, blobs also mark the sites of the formation of the most massive galaxies and of the intracluster medium. However, the blobs’ power source is a puzzle. By targeting optically-thin lines such as Halpha and [OIII], we have obtained the first measurements of gas kinematics in blobs, excluding strong outflows as the source of Lyman-alpha emission. I will present new results characterizing the large-scale environments of blobs and further constraining their power source via polarization mapping.