Gravis focused on his tiny world. It was barely a couple million kilometers big, which was incomparably tiny to Orthar's worlds.
However, this was only an embryo.
As Gravis looked at his world, he felt the sheer power he had over everything. No wonder Orthar could defend himself against the Opposer while he was inside his Cosmos.
Gravis could freely control the very Laws that made up his Cosmos.
If there were someone inside his Cosmos, they wouldn't be able to use the Laws in their surroundings as long as Gravis didn't allow it.
They would need to summon the Laws of their own Cosmos and invade Gravis' Cosmos.
However, they could only bring so much power over at once, and Gravis had access to all his power at any given time.
It would be like Gravis' opponent would only be able to unleash 5% of their power at a time while Gravis could unleash everything at once.