Keltham is not easily found, but he has taught this Carissa Sevar of blind-coordination focal points.  There should be a place that Carissa Sevar would think of after relinquishing Asmodeus, that Keltham would also think of.

Her first guess doesn't work.

Going to the Iomedaen temple nearest to Keltham's arrival point by the Worldwound does.

Keltham is not easily found, but he has taught this Carissa Sevar of blind-coordination focal points.  There should be a place that Carissa Sevar would think of after relinquishing Asmodeus, that Keltham would also think of.

Her first guess doesn't work.

Going to the ruins of the Iomedaen temple nearest to Keltham's arrival point by the Worldwound does.