I had been playing various builds of Ready and Waiting against Obliterator, but a few games ago I seem to have found the right combination, and now I am on a winning streak. The Octopus is the key.
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I have been avoiding Ready and Waiting against false gods when something else was available because of the bug that doesn't give you EMs when your opponent dies to an anti-mattered, vampired creature of his own. None of the suggested options in this thread seem to work as well against Obliterator, so I have been tinkering with Ready and Waiting, and I managed to get an EM today, killing him with my own creatures' damage while his weapon was frozen.
Get a Purple Nymph first. You don't have time to get unlimited Quintessence first, but you will need it eventually, because when his health starts getting low he will Gravity Pull his antimattered creatures. Congeal Shriekers to keep them from burrowing, and AM, LS, and Quint them all at once later. And if you get the Voodoo Doll you can hold his weapon at bay with an Octopus as well.