I will present results from the LABOCA/ACT Survey of Clusters at All Redshifts (LASCAR) project. LASCAR has used the Large APEX Bolometer Camera (LABOCA) on the Atacama Pathfinder Experiment (APEX) to obtain 19"-resolution 870um imaging of ten of the most massive galaxy clusters that were detected as Sunyaev-Zel'dovich effect (SZE) decrements in a 455 sq degree Atacama Cosmology Telescope (ACT) map. We have detected 870um SZE increments in multiple clusters out to z~1, which we use to study the physical properties of their intracluster media. We also examine the properties of background lensed submillimeter galaxies, and use our newly-acquired 2.1GHz Australia Telescope Compact Array (ATCA) imaging to disentangle SMGs from SZE emission near the centers of disturbed/merging clusters. The project benefits from multiwavelength follow-up at optical (NTT, SOAR, VLT, Gemini), X-ray (Chandra), and infrared (Spitzer) wavelengths. Included in our sample is the "El Gordo" system, an exceptionally massive Bullet-like cluster merger at z=0.870 with two prominent complexes of radio relics and a radio halo.