Hardcore mod is a mod increases AR and OD in the same way DT does, but not increase the playspeed nor CS nor HP. That mean: 200 bpm, cs4, ar9, od8, hp7 + HC = 200bpm, cs4, ar10.3, od9.6, hp7. It wouldnt have the capped at 10 like HR does. Could be ranked with 0.01x bonus but unranked is fine too, as a practice mod.