Perhaps Golgari should be rapidly acquiring regeneration/fast healing, first when you're under 0 HP and as the class goes on opening up to constantly... You could draw some inspiration from the 4th ed Revenant, perhaps?
This and the "Steal memories" ability strike me as rather worrying.Skill - A 13th level Dimir Secretkeeper may grant herself and her allies a +10 insight bonus to all skill and ability checks made against the identified creatures. This bonus increases to +15 at 19th level.
Skill will not usually come up, except in social situations, in which case this is absurdly powerful. Generally just not a very good idea.
Steal memories, however, will reguarly end a fight in one successful attack, since without a standard action, they can't attack or cast spells, which functionally leaves any opponent a non-threat under a continuous rain of attacks so long as at least one hits a round.