Power bond + gear monsters = summon ancient Gear Giant
No Power bond...
Kuriboh-> Multiply -> Masterking Archfiend -> linkuriboh and link spider -> Saryuja + Effect
If you have multiply only, you can search Kuriboh with old pal Sangan
Or
Cyber Pharos -> GY; Fusion summon Howitzer-> GY-> Cyber Pharos effect -> Power Bond -> Gear giant
Or... just sarcophagus your way through all that xD
Cyberse Synchron and Fateful Hour can save or bring your Gear Giant back
Obs: Don't fusion on your 1st turn, you can recover your monsters with gear workshop later.
You don't want your opponent taking control of your 9k atk monster