Using novas to power shards should be quite new...
Eternities costs 3
to rewind once, but for SoR to be applied on it, a flying weapon is needed, but then... protect artifact is useless.
Even an upgraded eternity needs 5
to be played, too slow for a "Mummy rush" like this.
If I were to make a full pharaoh timebow, i would not even use mummies...
Edit: I can imagine your idea in a time PSN though. Looks quite decent, but still, too quanta heavy for a rush.