I wouldn't give you an advise, you can do pretty well without my advise, but will share my experience with Souldrinker and the bombs in general. On my second account Souldrinker was the only meaningful champ for a long time and somehow i was forced to build him long before they buff him. He is still for the most of my dungeon runs main damage dealer. Yeah, if is really funny how those my two account developed over time - completely different approach for each of them.
Yes, bombs are both blast and fun in Arena and 2 x 30k raw damage is something that must be taken seriously. The Souldrinker himself has pretty good modifiers on his skills (probably one of the biggest A1 modifiers that i know of, thou my info are bit old and not any near complete). On arena he usually crit with his A3 for 2 x 18k - 20k+ according the target before the bombs to be applied and same numbers i usually register with his A2. And his all skill set is build to serve that bomb damage by reducing their time with every hit. Really love him. The he looks and works.
Now, there is one major problem with him and that is the bombs itself :) As hard as they hit, you actually have to make sure they will land and then they will stay on target until they trigger. And as hard Souldrinker hits, he didn't bring anything else to party, just big numbers.
The only way he will work well is when you build all other party members whit that bomb in mind. You have to be sure the bombs will land and explode - you have to have good accuracy, you have to be fast so enemy can't cast any block debuff, you have to make sure enemy will not cleanse the bombs, you you must find some way to prevent that and then you have to give Souldrinker enough time to live for another round or two reduce bomb duration or even trigger them. But when you do that i can tell the feeling is satisfying. Whatching those high HP/high Def champions fall is something that is worth the investment.
That is exactly the way i have to build my alt team = High Khatun > Umbrall Enchantress > Scartorsis > Souldrinker. Ifs fun and rewarding, but the only reason i cant recommend it is the fact that it will probably take completely different approach from what you follow now and most likely you wouldn't do it for the fun itself :))
