Bloodborne PS4 PVP gameplay rules are fairly simple to understand, the basic thing to keep in mind is the player which invades the other player is the guest who arrives in your world, and the host is the one who is being invaded by the guest.
If you are wishing to invade other players, you need to use the Sinister Resonant Bell or start a co-op session.
When the Sinister Resonant Bell rings, there are chances that the sound will attract a bell maiden or Bell Chiming Woman to your world instead, in this case you will become the prey instead of hunting other players!
Here you will have three cases, first is when you summon help, secondly if you are in the same area as the bell maiden or Bell Chiming Woman and lastly you are trying to invade other players but get invaded yourself.
But this is not always the situation as the bell maiden or Bell Chiming Woman will only make an appearance in your match. Once you find a player to invade and are done with the match (you will be rewarded if you win against the other player) you will return to your own world.
Tell us about your Bloodborne PS4 PvP experience in the comments section below.