This is an immortal who joined my ranks when playing as MA Tien Chi. She has a clear description that she is capable of healing afflictions, but she lacks the actual skill. Is this a bug?
She does heal afflictions. When you select her and hit spacebar to get the orders menu, you will find that she does indeed have the Heal Troops command. That's what you need to use.
I had her once, and I can't say she helped me the least :
A healing heroe with Tien Chi is not what I was dreaming of.
I would rather see an old and powerful mage, maybe with some afflictions like limp and/or crippled.
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10 times more numerous, by nigth and backstabbing.
Well, there is one, the other immortal, he is described be frequent astral traveller, whose body was buried once when his spirit was away, so he had to possess a body of an old leper. This one would suit you, probably :-)
IMO Ho Hsien-Ku should have the healing ability listed.