I finished the drow summoner quest today, so I'm 2 for 8 now. I got a human
type as
easy sacrifice, and there was some in the asylum Jkk showed me not far away,
which ended up being WAY easier than tracking down a suitable spider corpse
over 5k but not huge. I solo'ed the spider demon and all went well, so I'm
left to assume it must require solo defending the summoner during the
incantation. I'll try a medium sacrifice next, and hopefully it's not
ridiculous. Apparently the limit for that is not level 30 either, as some
suggested it might be. So that makes it a bit easier.