They crashed their ship into the dreadnaught and used it as a base of operations. They went toe to toe with the hive on their own ground, and they seemed to be doing just fine.
But the biggest part; the shield Brother's strike. They led a team that if succeeded, would've destroyed the dreadnaught and most of our solar system.
If they would've won, they would've defeated oryx.
"But oryx can only be defeated in his Throne World!!"
Oryx's throne world is in the dreadnaught. If they blew that up completely, where would the throne world go? No where, cause it would no longer exist.
If you have a counter argument, please come discuss, let's have a lore discussion, those are always fun
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Yes, they would have won but they would have destroyed most of our solar system with it, destroying the dreadnaught and his throne world would have caused a huge explosion of cross dimensional energy that would have destroyed everything. I think they say the same in the strike.