There will be one pet that can only be purchased using currency obtained through killing other players (opposite and same faction) on the Timeless Isle.
- On PVE servers, the mechanic for PVP flagging will remain the same.
- If you do not flag yourself for PVP, you will not be forced to participate in PVP.
- Those that use the Censer of Eternal Agony will be open for attacks, but they will not be able to attack anyone that doesn't have PVP enabled.
On PVP servers, anything goes (with or without the censer lol).
Hope this clarifies things! My blog post was written early on during the PTR, and was a first impression write up on the "PVP pet". There's an official Timeless Isle overview
from Blizzard which includes information on the Censer of Agony.