Some observations, I hope anyone can confirm or correct:

  1. After you are defeated you get.a 3 hour shield. Inconvenient, because this means you can get defeated another time before the attack points have regenerated.

  2. When you break your shield you immediately become a target for anyone in your range who is starting up PVP.

  3. When you attack one of your first 3 suggestions it is likely this person is already behind a shield. They often have been your suggestions for hours already.

  4. When you refresh and get another 3 targets it is likely these people are not behind a shield, because they are fresh targets.

  5. When you revenge it is very likely this person is behind a shield.

  6. You only see attacks in your log that were made when your shield was down.

  7. The attacks that are made on you when your shield was up are still counted in your defence stats for what that is worth, since they have not been reset since a few seasons ago. These defences do not count towards your trophy count.

  8. If you are attacked and defeated when your shield is up, your shield resets to 3 hours .

  9. If 8 is true it means that there is an extra benefit to attacking your suggested opponents, instead of just revenging. You get more trophies and you have an extra chance for a reset shield if the person you defeated successfully revenges.

  10. If 8 is true this means you can not be a better teammate than by a successful revenge.

edit: just had a nice test to confirm #8. Team mate Shilpa attacks and defeats me, and while her attack does not show in my defence log, my shield has reset to 3 hours.