Wrong Guys

'Death World Domain!'

'Kawa Blade Domain!'

Roan and Kentucky immediately activated their domains, and so did Eagon. Eagon's one seemed to be of the fire type, pretty common if you think about it.

Roan, as the Death World user, obviously could control it so that his own Domain wouldn't corrode Eagon or Kentucky's Domains. The same happened in Kentucky and Eagon's cases.

Kentucky used his limitless blade feathers in his Domain to block all the Rays of Light that the Crystal shot. Usually, the Crystal would be able to make its lasers dodge like it did against Roan's Scythe. However, Roan's Death World completely messed up with the Crystal's senses.