im of house cyaxan, that should be warning enough

i have over 2900 health, 75% fire resist, but the fire sorc merc just instagib me (latest death on level 11 map). i recall this fire sorc always doing extremely high damage throughout my entire play, gives me ptsd, sometimes she has a couple of chaos so i choose to fight and die every time. needs a big damage nerf.

2900 life and 75% fire resist is not good enough to avoid random one taps in red maps. Thats the baseline defenses for when you enter white maps.

If you want to unhide your profile people might be able to give you help to improve your build.

Sound like not enough health pool to be safe from one shots in t11 maps.

The Mercs are dangerous though. Occasionally one gets me and i'm on a build that has done ubers. I found with my build they were dangerous, but once I got to a certain defensive threshold the became fairly easy. It could be that you just need some more defense/health pool to get to that threshold.

Otherwise, if getting one shot, self cast guard skill might be an option if you have enough dps to keep the fight short.

If it is the Flamehand you are speaking of, im using that merc and it has some potentially high damage one shot skills that can ignite. Fireball and flame blast. It also can have flame surge which can get you with burning ground if you are susceptible to ignite and DOT.