How do you tank Titan Hard and keep hate the whole way as Paladin?

[cotti]

You can even use Shield Bash to get some extra damage in for more threat.

Shield Bash does not have a enmity multiplier, so it should be used only when you are safe from losing aggro. Used in the beginning, it wastes a turn that could be used in preparing another Halone combo or even Rage of Halone by itself, that even with a smaller damage should give more enmity because the multiplier in it is active even if not part of a combo. If OP is having trouble keeping aggro, be it his or his pals' fault, Shield Bash is the least useful attack for him right now.