I had a situation where the auto tapper killed me in Powered Cube. Board state:

I had a Hullbreacher and seven Treasure tokens out while at 1 life. My opponent had no nonland permanents apart fom a Talisman.

I had a Mana Confluence and six lands, and went to cast an Ugin, Eye of the Storms. Auto Tapper chose to use Mana Confluence over using one of my Treasures.

Issues here:

1) Obviously, auto tapper should not tap Mana Confluence while I was at 1 life instead of using a Treasure.
2) If auto tapper wants to tap a land in such a way that my life total would go to 0, it should display a very clear warning that doing so will result in going to 0 life. This might be easier to detect with 'pay life' effects rather than 'deals 1 damage to you' effects, but either should be detected.