Delirium??

I've now played through the Deli, Abyss, Breach, and Ritual questlines.

I prefer to farm normally using the Abyss and Breach tablets.

But what exactly is Delirium for?

It's a cool mechanic with Delirious and Grand Mirror, sure. But it just gets really hard, and I don't see the point of it. What exactly is it for?