It should be much easier if you separate your trap specialist and get through alone, then regroup past the traps using the teleporter pyramids.
You will learn the Source Vampirism skill yourself after you complete a couple of the quests related to the source masters, and perform the ritual again in Siva's cellar.
Until then, one character should be able to use sneak/invisibility to activate the waypoint, and the rest get by that way (though depending on the party formation, they may need to be careful when moving away from the waypoint, that they don't get too close; sneaking should help if that is a problem, or moving the characters separately, so they all take a safe path).
