Step 1. Activate Union Hangar, and use its effect to add A-Assault Core to your hand
Step 2. Normal Summon Gold Gadget, and use its effect to special summon A-Assault core from your hand
Step 3. Using Union Hangar's effect, attach B-Buster Drake from the deck to A-Assault Core
Step 4. XYZ summon Gear Gigant X using Gold Gadget and A-Assault Core
Step 5. Using B-Buster Drake's graveyard effect, add Heavy Mech Support Armor to your hand
Step 6. Detach A-Assault Core from Gear Gigant X to use its effect, and add Symphonic Warrior Guitaar to your hand
Step 7. Set Symphonic Warrior Guitaar in the Pendulum Zone, then activate its effect to special summon Symphonic Warrior Miccs from the deck (and discarding a card)
Step 8. Normal Summon Heavy Mech Support Armor using Miccs's effect
Step 9. Using Heavy Mech Support Armor's effect, special summon A-Assault Core from the graveyard
Step 10. Link Summon Platinum Gadget using Gear Gigant X and A-Assault Core
Step 11. Using A-Assault Core's effect, add B-Buster Drake back into your hand
Step 12. Activate Platinum Gadget's effect, special summoning B-Buster Drake from the hand
Step 13. Link Summon Underclock Taker using B-Buster Drake and Heavy Mech Support Armor
Step 14. Using B-Buster Drake's effect, add C-Crush Wyvern to your hand
Step 15. Activate Cynet Mining, discarding C-Crush Wyvern and adding Backup Secretary to your hand
Step 16. Activate Backup Secretary, special summoning it from your hand.
Step 17. Link Summon a Link 4 using Underclock Taker, Heavy Mech Support Armor, and Backup Secretary
Step 18. Contact Fusion Summon Summon ABC-Dragon Buster using Assault Core, Buster Drake, and Crush Wyvern in your graveyard.