Hitting an enemy gives them 1-4 stacks of 2.5% Brittleness. Debuff lasts for 5 seconds and can have a maximum of 16 stacks.
5-8% toughness on Chained Hit.
Your Grenades stick to Ogryns and Monstrosities. 6-15% Damage vs Ogryns and Monstrosities
20-35% Toughness on Elite Kill.
I change the Passic 'Get Stuck in' to 'Great Cleaver'
If you're planning to take on a Daemonhost, make sure to equip Curios with Corruption Resistance and always dodge to the side during the fight.
If you want to use this build in Havoc, swap out the Corruption Resistance Perks on your Curios for +4% Combat Ability Regeneration. It makes a big difference!
They help you quickly regenerate your Toughness. Try to stay close to enemies at all times, if you get caught out in the open, especially against ranged enemies, you'll run into problems.