ooc: I think Umber Hulks were useful for this kind of tactic, but sadly they are not in the SRD only the MM.
"With non-detection, invisibility sphere, silence, and dimension door, we should be able to get in. However, distance is a problem. Perhaps some illusions could mask our movement until we are close enough to employ our spells. It will take a large amount of our combined spell compliment to manage both in and out without a rest. Which means should anything require physical combat beneath the temple, I will most likely be joining those of you on the front lines with my staff." offers Tenebrynn.