You control a nontoken noncreature artifact with mana value one or less.
Steps
Activate Krark-Clan Ironworks by sacrificing the nontoken noncreature artifact, adding ({C} magic symbol) ({C} magic symbol) .
Scrap Trawler triggers, returning Walking Ballista from your graveyard to your hand.
Activate Salvaging Station by tapping it, returning the noncreature artifact from your graveyard to the battlefield.
Cast Walking Ballista by paying ({0} magic symbol) .
Walking Ballista enters the battlefield and dies as a state-based action due to having zero toughness.
Scrap Trawler and Salvaging Station trigger.
Resolve the Salvaging Station trigger, untapping itself.
Resolve the Scrap Trawler trigger, returning nothing from your graveyard to your hand.
Repeat.
Once you have infinite mana, you may use it to cast Walking Ballista, and then remove infinite +1/+1 counters from it to deal infinite damage to any target(s).