Well hidey ho.

Rico, your sorc must blow. My sorc has only a 56% absorb energy shield, 800 mana, 45% damage reduce, and a lvl 70 zon only removed all my mana, and only 100 hp, leaving me at 900 hp, and the zon dead from 1500 dmg nova. Now seeing as my sorc has maxed all resists in any difficulty (except hell, i got -10 poison res), and with the extremely fast casting from dual occy ring + occy I can whack anything quickly with nova, while still casting orb at a good rate, and as of late I have yet to meet a sorc that could survive 2 TS hits, even on norm with maxed lightning resists, if they can even survive 1 nova. Now about mephisto, his most damaging attack is that weird frozen orb like ball (I do believe its the same one, except it doesn't shoot shards). It does 50/50 cold/physical. with 0 cold/phys reduce you will take around 500 damage, which would make most mephbot's do chicken life, or would be too late with you being dead, and trying to do runs naked also cronic's advice isnt really sound, leveling up with firewall is a drag, and most of the time, meph doesn't stand still unless your standing next to him letting him try and swipe you with his hand (claw?), and orb/ts works perfectly, seeing as each shard does 300+, and can spew out over 20 shards, plus TS at high levels hits quick and hard, so thats about 2000 each second from TS, and meph only has 50000 life (or was that diablo?) so that would mean 25 seconds=dead meph, but with firewall you have a greater chance of getting killed since you HAVE to keep meph still, or you will do pathetic damage.