No source of damage other than contraptions, this includes damage from artifacts and traps.
I would suggest starting with screw mold and either transmission belt or the meter.
Then this is somewhat the priority:
- Ditch as soon as possible all the red cards through events that exchange or remove cards.
- Acquire/upgrade shield cards greater than shield up
- Have at least 1 consume all screws for shield cards
- Be sure to be able to generate 4 screws per turn on average
- Duplicate the presence of the prototype/popping wrist/shoulder cannon to ensure a constant flow of damage output
- Have a reliable way to defend yourself (stuns/shields)
Attempting this in solo mode will put you completely in RNG dependency, going multiplayer and working as support will simplify your life greatly.