-You can only use Procrastination OR Bone Wall at any given time, so unless you're expecting to face an opponent Bone Wall doesn't work against, you can probably drop Procrastination.
-Gravity Mark with Time Pends/Pillars works better than time mark with Gravity Pends; the way this is set up, you can't devour anything unless you get one of three cards in a 34-card deck, and even then you can only devour once every 2 turns.
-Keep the deck to 30 cards and put in Hourglasses instead of Reverse Time. Draw consistency is very important. If you're seriously worried about the lack of Reverse Time, you can always put in another Eternity, since it's unlikely you'll draw both copies in a game.
-The deck, other than rewinding, can't do much against a creature with decently high HP. You won't draw all six Scarabs in a game, after all, so your scarabs can't devour anyone with more than 3-4 HP, probably. Do you have any Pharaohs?
EDIT: I forgot about Mummy's Passive. I would say, 3xEternity, still drop the RT spells.
Quick count: At minimum, to make the deck's main combo work you need 4 cards.
-RT/Eternity, to rewind the mummy
-The mummy
-Death Pend/Pillar, to play the mummy
-Grav Pend, for Scarab
Of course, you aren't going to actually try to play your mummy off ONE pend/pillar. It would be more accurate to say you need to draw and play two or three. Also, you'll probably want to draw more than one grav pend to devour more often.
So, that's a 5-6 card combo, minimum, to get the deck set up. There's not much stall in here either. Bone wall costs death quanta, which you need for the mummies. There's only one copy of Procrastination and Eternity each (and Eternity is expensive). You won't get many Scarabs before the combo rolls out, assuming you can even draw the pends for Devour. Even after you combo, since you have no quint it's easy to kill the Pharaoh.
The idea's interesting, but it's ultimately impractical. Sorry.
