Throw the crown on the Paladin tank, and then he/she can divine light all nearby undead after taking a few hits so they're properly debuffed.
Ouch.
Man, some of the older PrEs are starting to look dull now compared to these newer PrEs :/
PS - unsure if the fort lowering will work with undead, as they're technically "immune to critical hits" despite whatever fortification you get them down to.
Curious on how it's implemented, though. If Rogues can eventually crit undead, golems, and the like....wow.