Still not sure what ability is doing this, but Yuela occasionally inflicts 999 damage to a creature.

maybe you have ninja dagger eq or something else that gives the death spell thing

The Death "effect" has a small chance to install kill (shown as basically doing 999 damage (you should see a skull behind the number)) with every hit.

Some characters have a skill that has that effect. Some weapons do also (I think many of Ragsmuena's weapons have it).

It's the 'Death' special attribute that some weapons and skills carry. In Yuela's case, it's almost guaranteed to be this: http://dl.dropbox.com/u/37207996/Death.png

Yeah, you guys are right--thanks!

OK, related. I'm seeing Death occur when Anastasia attacks. This is her stat block:

http://dl.dropbox.com/u/37207996/Anastasia%20Status.png

The only thing I can think of is that her Balt Bucket gains Death at max level as an unlisted effect. Can anyone confirm? The only other recent change was adding the Gladiator Ring, which I've never observed causing that.

Yes, that means it can be leveled up multiple times.