my merc emilio survives travincal most of the time. he is wearing an eth bugged forti, uneth andariel helm with a ral inside and an eth insight cv.
i always make sure that before i go trav with emilio, he has the chilling armor casted (from forti) because this armor blocks most of the hydras
that hurt him a lot.
so life-stolen-per-hit (from andy helm) and the chilling armor (from forti) are really helpful... and as liskod said, drinking potions