Doctor

At night the doctor saves one player: if the mafia shot them, they survive, and the prostitute's block disappears. The doctor can heal himself only once per game.

The healer who works in the shadows

At night: Protects one player: if the mafia shot them, they survive; the prostitute's block disappears too.
Goal: Keep alive those the town needs.
Tip: You can heal yourself only once per game: don't waste that chance.

In short

At night you wake after the sheriff and pick one player.
If the mafia shot exactly that player, they're alive and nobody dies.
You can heal yourself only once in the whole game.
A heal works for one night: you choose anew every night.
If you healed the one the prostitute visited, her block disappears.

The doctor is a town role. At night, after the sheriff, you wake up and pick one player. You can heal any living player. Yourself — only once in the whole game. You get one choice a night, and you can't change it.

With the automatic host there's limited time to choose, and the room owner sets it. With a live host, the host wakes you.

What happens in the morning:

the mafia shot exactly the one you healed: they're alive, nobody dies;
the mafia shot someone else: that person dies, your heal changed nothing;
the mafia missed (shot different people or not everyone shot): nobody dies.

When nobody died, everyone is shown only that the night passed without victims: it looks the same whether you saved someone or the mafia simply missed.

Doctor and prostitute. If that same night you healed the one the prostitute visited, her block disappears: in the morning that player speaks and votes as usual. You don't know whom the prostitute picked, so this may happen by chance.