When you reach the big island, send omnis in a suicide mission from below ;). In this way, you will soften up the land and if you are quick,
you will establish a foothold.
Then turtle until the island is fully mired. You can now send omnis to take out the ship spawner.
Spoiler
An energy mine will spawn and will help kill those particles by getting destroyed all the time. Screenshot below. (particles tend to get attracted to friendly structures, so the blob up there will vanish
Then just send some amped ships to cap the emitter off, and mission complete.