If you have 4 life you can 1/8 (def) a palladin and slowly but consistanly rush abysses, watch out for 4 way rooms, brutes can still fuck you up because they are faster than you, even if your pet sucks you can still use your seal to keep healthy.
If you dont have the 4 life, you want a 0/8 sorc and a MHeal pet and equips you can afford to loose, takes a little longer but is brain dead safe as long as you keep spamming your ability as it shoots round corners and shit.
For best performance you need a 4/8 (minimum) warrior with Jugg and Dblade, with practice you can rush an abyss in about 2 mins, depending on the layout.
(which I'm assuming you don't have because if you had 2 UTs and a 4/8 melee you probably wouldn't need advice on abysses.)
Regardless of what method you go with, watch out for the mages, (they fire the big slow missiles) even on a maxed knight a few of them stacked can wreck you, also when you get the hang of rushing, turn off safe walk, sometimes its better to take a step in lava than face tank a million demons because you didnt have the space to circle properly, oh yea, you need about 35-40 spd to keep up with the brutes, learn how to circle. Also a good rule of thumb is to go the opposite way to the most logical path to Malph, treasure rooms arn't really worth hunting your better off getting back into the realm and starting to hunt more abysses.
Source: About 1500 abysses, mostly on pallys and sorcs.