It depends. If you are using Fester or Painflare you would want to do a Ruin III followed by a Ruin II for the CD synchronization. If you are low on MP then do a Ruin I followed by Ruin II. Otherwise I just spam Ruin III or Ruin II depending upon MP and how much moving I need to do. To be honest I don't even use Ruin I anymore unless I'm sync'ed below level 54. Between Aetherflow, Energy Drain and Lucid Dream I rarely run out of MP unless I get distracted.