Hi, i can't seem to get the four brideges to stop moving and when i jump, i fall into the poison water which means i die all the time
I made it to the other side swimming the poison water and got the treasure but no artifact??????
plse help

I couldn't jump them either. The artifact is not there, so that's why you didn't get it. Swim back over. If you are looking for the artifact, then the Lich obviously has given you the quest. There is a key he also gave you that opens a door - that door is almost directly under the entrance hall (ie between the 2 sets of stairs that lead down from the first castle chamber. There are several puzzles to go, but the artifact and Adrianna's scroll and Mabba Mabbig are all down there.