Just finished a solo spear/block MS run. It turned out easier than I thought, I kind of expected to break a keyboard or two. Having only one character to deal with is always way more confortable than trying to keep everyone alive until the end of each fight.
Anyway here is my build before final fight :
http://i.imgur.com/uuMbUul.jpg +2 STR through medical machine
http://i.imgur.com/9UcZAy3.jpg
I economized as many resources as I could until the three deadly constructs fight to be sure to take them down easily. I burned and bombed the two cunts and threw acid on the ranged one to take it down gently. Grealty satisfying, this fight traumatized me on my first party run.
However I did not expect to be so short of SP on a solo run. In the end I didn't even open the strongbox and didn't get the regeneration potion that would have been so helpful for the last fight. I could have got 8 in crafting to open it but would have been too far in alch to mix the potion anyway. So I put the points in a last rank of spears and alch for acid splash.
I believe you need a minimum of 8 STR for solo hasta run. Otherwise you simply lack the damage, especially in the beginning with the scorpions and ants that you can't poison AND the pretty late hasta schematic.
Overall fun and easy run. Pulling the emperor on the balcony, throwing some liquid fire between him and I and taking him down netted with scaurus' spear was priceless.