You must have a strong merc if you got bad gear. If you got a weak merc, it's always going to be hard. Blizzard i a skill i don't like, it hits too randomly. Playing hardcore, i need to know the spells it.
I use hydra and frozen orb, along with a high level static field. High level static works on the entire screen, you lower the enemy hit points by 50% when used 5-7 times quickly in a row. Works on bosses too.
Hydra can be built up and cast while you move around, so it's good to use on hardcore.
Orb just deals big damage to enemies typically immune to fire and lightning, especially in act 1, the goddamn carvers and the devil dogs that shoot lightning balls. They wreck them.
But you should be doing quest bugged nightmare diablo and baalruns until you're high level, 75-77, and got decent gear. There's no point to venture to hell mode unless you got good gear and high skills. You will just struggle and it won't be fun. Hell mode is a different beast ... at least in hardcore. You can't rush into anything, because the right monster pack will kill you in 1 second.
D2:R