So
We played Kingsport today.
Leo, Michael mcglen and diana stanley.
And boy did "Yig" kick our ass.
We had gate burst off mythos cards, terrible rumors, the worst injuryes.

But among it all Leo Anderson randomly collected a couple allies in kingsport while closing gates. And he picked up "Terrible old man".

Terrible old man can heal up a sanity every turn, for the cost of a focus.
Leo can prevent the loss of a stamina or focus.

And "Yig" makes you lose a stamina and sanity every turn(we had no old one decks in play, just the Yig card.
And when Yig finally arrived we realised that Leo had been on the expedition of a lifetime all along. He kicked Yig sideways, with just a revolver.

It turned the negative experience upside down.

just found this errata_

Discard The Terrible Old Man if the Ancient One awakens.

Yyyyyup. I had to complain to make TTOM and Herbert West get discarded during final combat, for exactly this reason.

Terrible old man can heal up a sanity every turn, for the cost of a focus.

Leo can prevent the loss of a stamina or focus.

It's been a long time since I last played AH, so forgive me if I'm off base here, but IIRC, there is a mechanical difference between "cost" and "loss."

Costs MUST be payed in order to garner the effect they buy and cannot be negated by effects that protect against LOSS of the same currency.

Again, IIRC. It has been a while.

OP's point is that against certain AOs in final combat, you can completely negate the AO's entire attack and remain alive indefinitely. It's entirely to mitigate loss: no sanity or stamina cost is involved here.

Because of this loophole effect, many healing items have been banned from final combat (Healing Stone explicitly says to discard it. By the time Kingsport came around, FFG was less effective at spotting these potential loopholes).

Thanks for all info. We actually played another game today. With Kingsport and Innsmouth, and got "The terrible old man" as an ally again at random. And discarded him correctly. We still kicked Hasturs ass!