I'm at level 23 with 235 hit points and a 194 armor rating, playing on Adept difficulty.

I had just finished a long battle where I ended up killing 2 blood dragons back to back.

During the battle I was breathed on at close range multiple times and had enough time to react and heal.

Next, I pick up this side mission to retrieve a sword from Stony Creek Cave.

The bandits are handily dispatched until I sneak up on a rag-wearing bandit marauder (lvl 25 according to the console).

I order by NPC buddy to go in. The marauder lights him up with 2 shock attacks of some sort in about 4 seconds (NPC buddy is still going). The marauder then turns on me and hits me with what appears to be lightning. I lose about 5% off my health (it was at full). In less than a second another burst hits me and I go from a 95% full health bar to an animation of my body sliding down the hallway.

This surprises me a bit, so I reload and try this about 5 times. Every successive time, the marauder has to hit me about 6-8 times over about 2 minutes to kill me. I even walked up and started punching him to see how long it would take him to kill me.

Is it normal or a glitch that an NPC who appears to take a minute of attacks to slowly kill you in most cases, might fire off a lightning bolt and kill you before you can react in another case?

It's important to me as I play careful games where I quit and start a new character if I die by something other than a glitch.

Thanks!

That cave is filled with flammable gas. Could something have set it off? Were there explosions? I know that surprised me the first couple of times.

You know armour rating doesn't help when you're getting hit by magic, right?