Hi i need my merc to have 200 str for this insight and its lvl 80. can somebody tell me where to lvl him for the most optimal exp? and can somebody tell me when he will get to have 200str? it currently has 177 str. thankyou in advance

Socket his headgear/armor with Fal. Also, no point in using non-the cv. Use etheral, it only needs like 190 STR.

Your merc only gets exp when you get exp, so party kills don't count. I'd say that your best bet would be to do solo hellcows or something similar.

To get an act2 merc up to 200 Str without any additional gear, you need to be over level 90 (I socketed Bonehew with two rare jewels that had +ED before I realized this).

Don't go around monster killing to level up your mec if he's a couple levels lower than you, just strip him of his gear and buy a new merc with the highest level (should be your clvl - 1)

well when you buy a new merc doesnt it make the lvl of its aura back to lvl 1?

Additional Comment:
i have a vampires gaze is there how do you upgrade it and ill put a fal in it

lazruck will socket his helm for you (one of the first quests in act V). Your mercs stats are independent of the lvl you hire him.. there is no bonus to hireing a merc early as to late; however an act 3 merc from normal will have better stats than and act 3 merc from hell so you should always hire your merc in normal (obvious exception, NM - a2 mercs for a specific aura) Never hire anyone in hell. If for some reason, you love your mercs great name perhaps, you want to keep the merc, play private games alone and let him or summoned minions get the kills. Mercs only get a small percentage of experience for monsters you kill. (conversley monsters he kills you both get full exp).