Activate Goblin Bombardment by sacrificing the creature with Grafted Wargear attached.
When the creature dies, One with the Kami triggers, creating a number of 1/1 Spirit creature tokens equal to that creature's power.
Resolve the Goblin Bombardment ability, dealing 1 damage to any target.
Activate Grafted Wargear's equip ability by paying 0, attaching it to a Spirit token.
Repeat.
This clever sacrifice loop transforms the zero-cost manipulation of Grafted Wargear into an engine of endless devastation. By feeding a creature equipped with Grafted Wargear to Goblin Bombardment, you trigger One with the Kami to flood the board with Spirit tokens based on the fallen creature's boosted power. Since Grafted Wargear's equip cost is a mere zero, you can instantly reattach it to one of your newly minted Spirits, preparing it to be sacrificed right back to Goblin Bombardment to sustain the infinite loop of damage and tokens.