last boss is kind of cracked. without a build that removes status conditions from enemies, he's unbeatable. problem is that it basically invalidates the majority of different builds unless you either have a stack of remove status potions or an extremely rare accessory that let's you do this. kind of lame.
Nah, there's a fair few ways to beat him.
I've taken down The King using an straighforward armor+Sword build (Just let the spikes slow down, and with spikes of your own beat regen), an Arrow build (Who cares about spikes if I am long ranged!) and a Metal Wand/broken ring build. It's doable, just a bit tricky and weird.