why is power word kill 9 th level spell when i cant kill it even a spider?
i dont use it. instead i use empowered finger of death.

It's something to do with the no saving throws allowed I think [img]smile.gif[/img]
It does work, provided the enemy doesn't have a supreme magic resistance and/or more than 100 hitpoints at the moment of casting.
Alternatively, you could be casting the spell on the ground instead of at the spider. In that case it will kill up to 10 creatures with 20 hitpoints or fewer left over.

I'd probably go with Wail of the Banshee for level 9 destruction spells, rather than an empowered FoD. Mostly because all the empowering does, is have the spell dead 1.5 x 3d6 points of damage when the character makes the save, whereas the Wail has a higher DC and affects multiple monsters all around you. It also comes with greater range, and as they are both Necromantic spells, a spell focus there is no excuse either [img]smile.gif[/img]
The one situation where FoD would be more useful, is where the enemy is immune to death magic or has unbeatable saves in any case. You can then use the spell hoping it will actually fail, and deal the 3d6 damage. You would be better off with a Magic Missile then, though.

but why is PWK 9th level if you only can harm a goblin with it? With empowered FOD i can kill instantly 75% of creatures, and if dont kill them, i do them good demage.

It's a high level spell mostly because it kills without allowing anything like a fortitude save to avoid the death effect. If you don't have sufficient magic resistance (or immunity to death magic) and you don't have enough hitpoints, or allow yourself to get so wounded, you are dead, period.
There are more powerful (in most situations at least) level 9 spells out there by far though, I'll grant you that. It's most likely level 9 because it is under the 3E rules, and that's so because apparently it's 'balanced' that way. I'm sure they put a number of great thinkers on it [img]smile.gif[/img]