Increase probably of death scarab bites having side effects.

In particular, the draining effects should happen more consistently.
Make anubis guards' quarterstaves visually distinctive in tiles.

As far as I can tell, the equip tile for this isn't actually in use
anywhere else, and it makes for a good visual explanation of why they're
wielding staves to begin with.
Brighten the death scarab tile a bit.

The legs still blend into the floor somewhat, but it is more visible in
general.
Buff scarab bites further by adding a negative vulnerability effect.

A scarab bite now has the following:

1) 50% chance of inflicting rN- if the target does not already have it;
2) one of drain life or drain speed;
3) vampiricism.

rN- increases susceptibility to draining effects just as with other
negative resistances. Notably, a target with rN- can be killed by
torment.