another question: i stole a druidic staff, and it dealt the final blow (i was at full health before it hit) on an AI4. i earned 82 electrum instead of the standard 80 in EM. i couldn't take a screenshot, but is this a bug?
When a staff (or any creature with the regenerate active, really) deals the finishing blow, the game ends after it heals you, but before the game makes sure your current hp is no higher then your max hp. In 1.29, this would result in you receiving only 41 electrum, as you get a bonus for having more then 100 hp, but do not receive the elemental mastery since your current hp is not equal to your max hp. Version 1.30 fixes that simply by making you get the EM bonus if your current hp is more then your max hp (or equal to it, of course), but does not change the fact that your health is at 105/100 (or similar). So this could still be considered a bug, but the difference is very small (+2 electrum, whereas the old version would put you at -39) and fixing it would require a lot more work, so it isn't likely to be fixed anytime soon.
tl;dr: Interaction between various game mechanics left you at 105 health out of a maximum of 100 health, so you received a bonus for having more than 100 health.