Not really worth orchestrating “runs” at this stage, imo – just push through to Act 5.
What level is your sorc? What kind of mercenary do you have, and what level is he/she? Cheap, easy to make runewords that will make you and/or your merc plenty powerful include Leaf, Lore, Rhyme, Stealth and Insight. A good strategy with Mephisto is to let your mercenary engage and keep him topped off with Rejuvenation potions while you spam Static Field. This will get Mephisto low enough to finish him off in just a few casts.
When you still don’t have decent gear at all, the two best runs you can do are Andariel and Mephisto, because they have high chances to drop a lot of common uniques that are useful. Mephisto is a little harder, so if you find him too difficult you could just run Andariel for a while. One helpful hint is that you can take a few antidote potions before fighting her, and feed a few to your merc, to max out your poison resistance.
But a sorceress should be strong enough to be run Mephisto with just gear that’s easy to get. All you really need is 63 FCR, ideally 86 FHR, and some resistances. You can get what you need from Lore, Stealth/Smoke, dual spirits and some jewelry. The trickiest bits there are finding a plain Monarch (which will get 4 sockets from Larzuk) and a Lum for Smoke.
What does your build and gear look like right now?
Sorc vs Meph is one of the easiest bosses… use the moat trick to keep him at bay and attack him from afar. Meteor and Blizzard work best here but you can do it with Lightning/FB/Orb. What level are you btw…? As far as places to farm, don’t really have much options aside from just killing everything especially champion/rare packs.
Your in normal, no point in doing much MF runs at this point.
You should be somewhere around level 21-25 by A3 Meph.
You should have yourself a Stealth armor, farm the runes in the tower, purchase the 2os white armor from Charsi.
Leaf staff or an orb/shield, focus on resists. Get boots, gloves, belt, all Fire/Light/Cold res focused.
Tele to meph fast, static him down to 1, 1 shot, complete. Just learn his attack timing and dodge the attacks, hit him with yours.
Take out your items from your merc, go to act 2 and buy Combat merc with prayer aura. It heals over time. You are sorc so you need merc who can take some heat and lure enemies to him and survive for a while. You cana try to buy him poleaxe in gamble. best with life leech so he can tank for a while.
dont add more than 15 points into dexterity (its usefull against duriel but you are past that.
dont add points into energy
your vitality is too low because you wasted points into energy.
I suggest you to keep horadric cube with you always, its good additional storage space in inventory.
About the skills and build. Fire builds are not good for playthrough because you will struggle in certain places. Its much better to play cold builds. Btw place one point into:
Teleport
Warmth
Frozen Armor
Static field
This is basic setup for any sorc basicly. Must have skills with 1 point invested only.
About your equip:
pick up and save all gems, jewels and runes (you can combine gems in cube together into higher versions)
Buy 3 socketed Breast plate from Fara (act 2)
Buy 3 socket Large shield from Fara (act 2)
Buy 2 socket helm from Fara (act 2) - vendors reset their offer if you go out of town and back so use that strtegy untuil they sell what you want.
Socket breast plate with atleast 3 level of quality rubies. Helm with sapphires.
socket large shield with Topazes or combination of topazes, ort, ral, rubies, you need higher fire and lighting resistance.
Its usefull to buy two 3 socket large shield actualy so you can make in it Ral ort tal rune word when you got runes as reward in act 5.
keep buying heavy gloves and heavy boosts in gamble until you get some with atleast +15% magic find bonus.
You need to starting using sorceress Orbs+shield, staves are not good generaly speaking
drink few antidoted and thawing potions before fight with Mephisto.
If you still can use skill/attribute rest
relocate stat points so you have 60 strength and rest points all into vitality and keep investing in vitality after that.
+1 skill point into Static field, teleport, warmth and frozen armor
5 points into blizzard, rest into Iceblast and then continue level up blizzard/cold mastery and ice Blast. ( I usualy prefer to reset skills again on nightmare. and go with frozen orb instead of blizzard)
If you cant use skill/attribute rest
You need to buy staff with static field skill from Ormus and use it to lower HP of monsters so you can kill them more easily with your dmg skills. Static field is great against bosses.
Since you kind of screwed up with your stats, i suggest you to use /players 7 command temporary and keep running Lower Kurast(act3) few time and click all bojects on map. This should help you with some equip, most importantly gems and charms to increase your life and resistances to compensate lack of vitality. If you need runes, do some Countess runs in forgotten tower(act 1)
OP is obviously leveling as fire, which is fine especially with Leaf staff. He does not need to respec or stack mad resists. All he needs for Meph is 1 point in Static Field and another point in Teleport. The rest is just gear: resists from this or that, and pieces that are easy to make by farming runes from Countess (Leaf, Stealth). Lore is a bit harder, but still doable.