@dudeglove: You're forgetting Executioner's Chariot. If you ask me, that boss relies on the same principle as Bed of Chaos (environment triggering), except it's actually a pretty well designed boss fight. Unlike Chaos of said Bed.
It's hard, but not impossible to do that fight another way by basically taking pot shots. Skip to about 6 minutes in.
Once it's down to about a 1/3rd of its health, the Chariot can no longer make the jump across the pit, and can then be one shot.