No catalyst: [Necramech Vitality], [Necramech Repair], [Necramech Rage], [Necramech Flow]
0F: [Necramech Vitality], [Necramech Steel Fiber], [Necramech Repair], [Necramech Rage], [Necramech Streamline], [Necramech Flow], [Necramech Augur]
1F D: Add Necramech Intensify
2F D: Add Necramech Thrusters
3F V: Add Necramech Hydraulics
4F -: Either no change or swap in Necramech Efficiency or Necramech Slipstream
5F -: Add [Necramech Efficiency]
6F V: Flex slot, add any you like [Necramech Slipstream], [Necramech Deflection], [Necramech Continuity]

The most important mods are [Necramech Repair] and [Necramech Rage], this combo will make you practically invincible with some smart Storm Shroud usage and get back mana for Storm Shroud and guard mode when you take damage, then boosting guard mode uptime with [Necramech Slipstream] and [Necramech Flow] would be my second priority if not going full build. after the first forma you only add mobility.