Have you tried it -Phase Shield, + Fog Shield, + Enchant Artifact, (maybe) + Lightning(s)? Should help free up more for PU, while still giving you the stall you need.
It's a trade-off: 40% DR instead of 100%, but your OTK should come off faster with the extra and fewer cards to draw through.
The enchant artifact isn't necessary because hourglass baits. Plus, I need at least 1 dragonfly+immo (along with a nova) to cast it, so I'll probably end up discarding it most of the time.
I just tried it with a Fog shield. The problem with 40% miss chance is that 60% is usually enough to kill me, so I end up discarding it or replacing it with a Phase Shield.
As for Lightning, killing one creature doesn't really prevent me from dying by the hands of the 5 other creatures.
Dimensional Shield truly is the cheapest viable form of protection, both in quanta cost and deck space.