Talk:Operation Eyes of Blight/@comment-50.117.41.76-20141220013211/@comment-17703786-20141220014828

They do tell you in the message:

"Take note Tenno, the Disruptor is forged using recently discovered Omega Isotopes. These are a by-product of a Fomorian’s core and will only appear in and around planets with a Fomorian present. "

So any planet with a Fomorian present is where you can find Omega Isotopes. Currently there are Fomorians on Venus and Earth, so you can find Omega Isotopes there.