Implacable
(DR330 p84)
Resilient Rage – You gain +4 bonus to Dexterity
and Constitution, a +2 bonus on Will saves, and
a +1 bonus to your Damage Reduction (DR 1 /
— if you do not have any yet).
Greater Resilient Rage – When you are in a
Resilient Rage, you gain a +6 bonus to Dexterity
and Constitution, a +2 bonus on Will saves, and
a +2 bonus to your Damage Reduction (i.e., at
13th level, goes from
DR 3 / — to DR 5 / —).
Mighty Resilient Rage – When you are in a
Resilient Rage, you gain a +8 bonus to Dexterity
and Constitution, a +2 bonus on Will saves, and
a +3 bonus to your Damage Reduction (i.e.,
goes from DR 5 / — to
DR 8 / —).
I think you can combine that with the Boar Totem variant (UA p48), trading Fast Movement, Uncanny Dodge/Improved Uncanny Dodge, and Trap Sense for Diehard (only) when raging at 1st, +2 rounds to rage at 3rd, and +1 DR at 7th.