As someone who’s designed 2 bases in the Crevice, it is a formidable task to raid. Last time I was offline raided, there was corpses everywhere from the attackers and they had spent 3 hours trying to get in and only destroyed a single wall (not even meant for defense) a crenelation, and merely damaged the gates for about 1000 hp (out of 200,000).
Its not impossible, its daunting, but not impossible. I’d imagine Set could do a number on the gates in front, but if the main loot is honeycombed inside, you may need to summon a few set snakes.
The issue with the Crevice is its a double edged sword. While being nearly impregnable to attack. It is a poor choice for anyone who wishes to attack from it. Map rooms cannot fit inside. This requires defenders to sally out from one of the three entrances. If you can’t get in, you can definitely KEEP the defenders from coming out.
The trick here is you’d need to lay a seige. Get multiple clan members to constantly harass it and maybe even more then one clan. Because lets be honest, letting someone get established in the Crevice is the RL version of allowing a country to have nukes. You need to band up and take them down. As they can be a serious threat to the entire server base if not dealt with due to being resistant to retaliation.