The helpfile says:

Syntax: commune 'soul citadel'

By calling upon their deity to form a spiritual citadel around their sense of
spiritual and physical awareness, a priest may commune this powerful
supplication to render the priest resistant to all attempts to make him or
her slip from consciousness.

And for soothe:

Syntax: commune soothe <target>

Healers can soothe the battered nerves of other adventurers, boosting their
morale and lessening the negative emotional effects that various forms of
combat might inflict upon them. The supplication will also lessen the impact,
to a small degree, of magical maledictions that lower physical strength.
Soothed already by their faith in their deity, healers are unable to soothe
themselves.

See also: MORALE


But an evil healer does not have these in the supplications list. I assumed this means evil healers don't have them, but it's not explicitly mentioned in the helpfile unlike the cases of Vitality, and Turn Undead, and Divine Bond.

Added mention of alignment.