Ischaldirh wrote
The octagonal key, along with another oddly shaped key, are carried by high-end grudge monsters -- as I recall, my namesake has one of them. If you can kill him then you more than deserve the contents of the chest. However it's much easier to simply blast the chest with a wand of striking, or using a SoCM to change the box into something softer then kicking (or eating) it open
Doesn'tpaydoesn'tpaydoesn'tpay.
Really, afaik it takes just about 18 LStr and ordinary unenchanted iron boots of kicking to break the lock open. Or some 20+ AStr to throw the chest on one of the meteoric steel walls for the same effect.
If You can get polycontrol and polymorphitis, for example, from a staff of wondrous smells or a magical mushroom (careful!), I think a veteran or even rookie guard is enough to do it, so don't waste charges on wands of striking, or even worse, socms and wishes. Really! You can get 20 AStr just by blocking a carnivorous plant's attacks with something relatively heavy.
But the chest-polymorphing idea is sum good shit, yo.