Crusader is pretty much the best way to go for the possibility of invulnerability in melee.
With the Roots of the Mountain stance you are incredibly difficult to move. With a tower shield, shield specialization, and shield ward you are incredibly difficult to hit with anything.
Strongheart halfling
Crusader 10
Shield Specialization, Shield Ward, Combat Focus, Combat Stability, Combat Vigor
Belt of Magnificence +2, Tower Shield +2, Mithril Breastplate +1, Longsword +1, Crystal of Bent Sight, Crystal of Adaptation, Ring of Sustenence
While in Roots of the Mountain you gain a bonus of +24 to resist bull rush, grapple, disarm, overrun, and trips. With damage reduction 2/-, steely resolve 15, and fast healing 4 you are almost unstoppable with pure damage. With the crystal of bent sight you do not have to worry as much about gaze attacks, crystal of adaptation gives you endure elements to ignore the heat and cold, and the ring of sustenence allows you to go without food, water, and almost without sleep.
The items for this character are not heavily depended upon they simply make the character more able to do what he is already doing.
If you want to go kind of a crazy route then here is an idea.
Feral Strongheart halfling
Totemist 9 with all 3 racial substitution levels
Expanded Soulmeld Capacity, Shape Soulmeld Lucky Dice, Martial Study Charging Minotaur, Martial Stance Stonefoot Stance, Bonus Essentia
Psychoactive Skin of Ectoplasmic Armor from Complete Psionic, Monks belt with Strength +4 on it
Melds of Manticore Belt [Totem], Lucky Dice *hands*, Totem Avatar [Shoulders], Wormtail Belt *waist*, 2 others to taste
5 melds plus Lucky Dice, 8 essentia, 2 binds (crown, feet, hands, arms, brow, shoulders, totem)
Strongheart halfling
Totemist 10 with all 3 racial substitution levels
Expanded Soulmeld Capacity, Shape Soulmeld Lucky Dice, Martial Study Charging Minotaur, Martial Stance Stonefoot Stance, Double Chakra Totem
Psychoactive Skin of Ectoplasmic Armor from Complete Psionic, Monks belt with Strength +4 on it
Melds of Girallon arms [Totem], Kruthic Claws [Totem], Lucky Dice *hands*, Wormtail Belt *waist*, 2 others to taste
5 melds plus Lucky Dice, 6 essentia, 2 binds (crown, feet, hands, arms, brow, shoulders, totem)
The first is fast, very hard to hit, heals any damage dealt back, and has a crazy ranged attack. The second is not quite as tough but he does have 4 attacks a round that deal massive damage.