Madstone Rage

The Madstone Rage effect can be caused either by random contact with monsters in the Madstone Crater quest, or by the Madstone Boots raid loot. The duration is 2 minutes, and it provides a +2 bonus to strength, a +4 bonus to constitution, a +4 Natural Armor bonus to AC, and a 20% attack-speed boost, and increases your BAB to equal your character level. However, characters cannot cast spells while in this rage, which includes activating spells from items (except potions) as well.

The three different ways to acquire Madstone Rage stack with each other for strength and constitution, but not for other effects (allowing possibly +6 str +12 con).