User blog comment:Crimson and Darkness/Volume 25 discussion blog/@comment-2602:306:CD9A:C860:D9E5:F379:39CA:57B5-20180603215326/@comment-28884330-20180608092417

It's probably just a flat increase in power (which becomes greater in accordance to the King's power) rather than an exponential one unless the pieces used are mutation ones, since they can handle much greater stress.