Single Play, what am I missing?

I started a lightsorc in SP. Lvl 86 now, have Infinity, Crescent Moon and Call to Arms. And still I cannot kill the Ancients. The moment they hit my merc he dies, instantly.
There 's always a light immune among them so when the merc dies, it’s game over.

Been playing this game, well D2, D2LOD and now D2R, for over twenty years, I killed them Ancients 100’s of times on my own, and all of a sudden, I cant kill the Ancients anymore.

What am I missing?

are you on player 1 difficulty?

Don´t know if that is the advice you are looking for but revive Ancients, if there is lighting imune use town portal and respawn them until they are immune to other elements.

On hell difficulty, at least one is always light immune, cold immune and fire immune.
You can burn thru your TPs to your heart’s content and there will always be at least one immune to lightning.

yeeeah, I know where I got mistaken. I had trouble playing with Sorc with Frozen Orb and meteor and this helped me until I got no fire AND cold (like Lighting and Fire, kill it with Ice) imu together so I could hurt them with something.

I ran a couple 100 Mephruns, till I got some better mercstuff- more LL and res, so after another couple try’s I started to hit them ancients and tele to the other side of the screen to keep my merc alive.
That did the trick, I spend only a couple of life potions. I was very happy to finally kill them.

Thanks for your responses guy’s.