I came here to thank and abide to this guides, tho I did a bit different. Without speaking to Tonn, I went to the first two towers and killed every risen there - Beside the risen glitched inside the rock that sustains the first tower, there is another by a mini island which I didn't see in my previous attempts. Then I swam to the third tower, where I killed EVERY RISEN, including four by the water - which I supposed are the ones that comes out when you kill the elite, but I killed that pack, anyway. Then I killed the others in the way back to Tonn, revived all Sylvari, spoke to the Tactician, and came back to pick Tonn. He blewed all the towers and I managed to talk to him in the end. Thanks for those who spent time to discover this walkthrough. ^^ Hope mine helps as well.