Strongest Builds of All Time?

cast on death burned miscreations ;)

As in meta domination: old Vaal Spark and old CoC Discharge.

As in raw power:
Old 100% chaos conversion with double dipping poison and it's various builds.. In my opinion you can't top that. Like take a fast hitting spell, make it so you can't take reflect damage from it and add a strong dot that scales off the same modifiers that increase your base damage.

Old Voltaxic spark and dual consuming dark firestorm where pretty strong. But my pick would be old Vaal Molten Shell converted to chaos with Scold's Brittle. I think Mathil made a variant of this build during Perandus league. Charge up VMS with flameblast in a 4 link and then just shield charge into packs. Old AOE cleared packs as you went by. When facing boss just hold down flameblast and dish out many VMS procs per second. Damage was enough to kill uber phases in a fraction of a second.

Another honourable mention would be old Voltaxic using Lightning Arrow with pierce and old Frost wall. Use LA for clear and cast many frost walls on top of boss. Then you would attack with LA and it would pierce frost wall but interact with it as the projectiles went by, generating many lightning bolts that could wreck anything instantly.

LL ST and switching ST to moltenstrike or BF for bosses