We present and explore deep narrow- and medium-band data obtained with the Subaru and the Isaac Newton Telescopes in the ~2deg^2^ COSMOS field. We use these data as an extremely wide, low-resolution (R~20-80) Integral Field Unit survey to slice through the COSMOS field and obtain a large sample of ~4000 Ly{alpha} emitters (LAEs) from z~2 to 6 in 16 redshift slices (SC4K). We present new Ly {alpha} luminosity functions (LFs) covering a comoving volume of ~10^8^Mpc^3^. SC4K extensively complements ultradeep surveys, jointly covering over 4dex in Ly{alpha} luminosity and revealing a global (2.5