Lightning Tendrils Race Build Help

I've just ripped in the 4 hour Piety Kill race, playing a scion and I thought I'd ask for any advice for the next race. I ripped to a rare discharger. Oh well.

I quite like the Piety kill format and I've watched a few race streams.

I knew of the Lightning Tendrils build and have seen it in action, but although I did some digging before the race I could not find a race builds guide thread or anything with the general build tree.

Would anyone be able to tell me what's wrong with the tree below, or even link a viable tree for the 4-hour format for a Lightning Tendrils, Fire Trap crit build?

Scepter wise is it better to have a +1fire/+1lightning combo and does that top any spell damage, cast speed stats?

Also, when do I start putting on chest armour?