If the Risk Die comes up '1' when attempting Death Word, your attempt to draw upon the most fell of magical energies goes awry, and you suffer 1d4 HP of injury per level you hold in magic-user or a subclass of the same (and nothing, not even Death Ward can protect you from this harm) — and these dice explode. For each time beyond zero that you have already successfully employed Word of Death since your last long rest, increase the damage die type used on a failure (i.e., a '1' result on the Risk Die). If you've used it once before, and it failed on your second attempt, you'd suffer 1d6 HP of injury per level you hold in magic-user or a subclass. If two times earlier today, use d8s, etc.