I haven't actually gotten to the tower boss yet, but based on subanark's description I suspect lifesteal might be the way to go. You'd need a little over 600 piety with Dracul to make it work, assuming you have both the Vampiric Blade and Taurog's shield (probably best to take the -2 shield from the blacksmith, too; not sure if it's feasible to also go for Vine Form since you won't get Earthmother until after Dracul and won't have much piety fodder anyway, but once Blood Hunger gets expensive enough the math might work out in favor of an earlier switch). That shouldn't be too hard with a Dwarf Bloodmage and the Agnostic Collar. Hardest part will be actually getting to the boss in the first place. Honestly, I think the trickiest part of the tower is the deity setup; you're stuck with Taurog until you can clear level two, and his boons are outright cancerous in this dungeon (absent strategies that involve tedious min-maxing such as the above).
The new Venom Sword should be handy for CYDSTEPP Rogues and similar combos. With high damage and low defense, even one additional hit can make a huge difference in the amount of bonus experience you can claim.