Trying to build super-hero, but he dies too easy!

[StellarRat]

So, I took my best hero (39 HP) gave him the Obsidian Armor, Black Plate Helmet, a ring of regeneration, anti-magic amulet, the multi-spectral sword, and the Druid Boots that keep you from getting tired. I sent him off to wipe out a small group of lizard dudes (I think there were 30 of them and a priest). He got killed! From the description of the Obsidian armor and the ring of regen, it seem to me he should have been getting HP back every turn, but this did not seem to happen. What am I doing wrong? Note: The Sword was highly effective and I was not taking damage from using it.