How to change the difficulty of a field in GemCraft Chasing Shadows?

Solution 1:

They need to be unlocked before you can play them. Like other Battle Traits, they are unlocked by beating certain fields. For Glaring difficulty you need to beat field K4 and for Haunting difficulty you need to beat field T6 which you can only play if you have the Magician Pouch.

After you unlock it you can play any field on that difficulty even if you didn't beat it yet.

Solution 2:

From armor games comments: thunderrider Anamatron • 5 hours ago

"Glaring"(next step up) is found in the K sector I believe. Haunting, the highest difficulty, is only for premium, but has to be found in the wilderness after bought. Hope I helped.