There is a 5th Chest located after you defeat The Templar WITHOUT letting him teleport and your group getting marked by the oracles. Once you defeat him while doing this the chest is located just before you jump off the last part of the secret passage. Instead of jumping off you will turn to the right and there will be a small gap in the rock, crouch through it and the chest will be on the vex gate. This can be done on normal or hard. If you need a strategy that works you can cheese him with my guide for after the patch: Forums/t=6804862/new-way-to-chees...mplar.html