Something like this, perhaps:
7t4 7t4 7t4 7t4 7t4 7t4 7t4 7t4 7t6 7t6 7t6 7t6 7t6 7t6 7t8 7t8 7t9 7t9 7ta 7ta 7td 7td 7xx 808 808 808 808 808 808 80i 80i 80i 80i
(based on Pesty FG Deck)
Putting in 6 pests to increase the chance that they come early. If you don't get the Voidance until later, no big deal. If you get it after fractalling enough pests, you could then clear the rest of the pests from your deck. Or if you run into an opponent that has already played an Eclipse you could remove them from your deck. It would basically make this card a specialized Hourglass/Precognition.
Or for Entropy Rainbow:
52n 6qq 6qq 6qq 6qq 6qq 6qq 6qq 6qq 6qq 6qq 6rn 6rn 6rn 6rn 6u3 6u3 6u3 6u3 6u3 6u3 6u6 71b 71b 71b 74b 74b 77f 7do 7do 7do 7gp 7gp 7n3 7q8 7xx 7xx 7xx 7xx 7xx 7xx 80h 80h 80h 80h
Increased the number of towers, shields, and creature control to improve the chance of them coming early. Replaced Hourglasses with Voidance.
One question in the development of this card is if the target should disappear along with its copies. If it stayed, it would help rainbows and the like remove unneeded duplicates before they even show up. If the target was removed as well, this would give fractal decks more room to fractal.
To increase its playability maybe it should be a 0 cost Permanent with a renewable 3
activation cost?