Sounds like a lot of fun!First up, I'd try not to kill it... The wizard who made it is going to be powerful and I'd get annoyed if someone blew up my XX,000 GP toy.
A carefully worded Divination might cut down the amount of searching you need to do considerably?
Could you scry the room with something like Clairvoyance - might well be protected, but it could be worth a go...
If your mage has it, Wall of Force could be useful. No SR so Mr Golem can't get through it. Only 9 rounds duration, but that could be useful.
If you've got some tanglefoot bags they could buy you some time. It will have no problems making the reflex or strength checks, but it will still slow it down to half speed for 2D4 rounds.
Hitting it with electricity at the same time should slow by a further half with 1 move or standard action, for 3 rounds. A wand of Electric Substituted Acid Splash will cost you 375 for 50 charges... if allowed.
A combination of the 2 will reduce it to 5' move, 1 single move or standard action per round. As long as they stack.
Could someone, perhaps the barbarian, 'bait' it into following. Along with someone with electric attacks and the tanglefoot bags, lead it a long chase around the building.
The rest of you get to the top of the tower, either by flight, dim door or similar, possibly even climb and cut through the roof with the adamantine weapon?
While it's busy chasing the others you'll have plenty of time to search?
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