@ K1W1:

I really really like Nather Shadow as a card in Dredge. But I think it's only playable with Phantasmagorian.

If you don't have the LEDs, this is not really a problem imho. Just play the best, fastest and most consistent list one can build w/o LED. Aside from my LED list I'm also playing a LEDless list and LED isn't really strictly better.

Basically, I would take out the Shadows and play 4 Breakthroughs in those slots. I personally like me some more Tireless Tribes as well, but that's up to you.