Jotunbrud (aka Powerful Build)

[Curmudgeon]

(Why would Jotunbrud stack with Powerful Build? It grants Powerful Build.

Not close. Not even in the same city.

Jotunbrud doesn't grant everything Powerful Build does, because it lacks any help with weapons, as Roderick_BR pointed out. Jotunbrud plus Monkey Grip plus Weapon Focus plus a masterwork weapon is almost as good, except that there are still a bunch of things that make special exceptions only for Powerful Build and not for Jotunbrud -- like every one of these feats:

• Rock Hurling
• Improved Rock Hurling
• Fling Ally
• Fling Enemy
• Knockback
• Rampaging Bull Rush
• Powerful Wild Shape

Powerful Build occupies a different state entirely than Jotunbrud.