If you're using a skeleton's wellbeing, PoE goods casts in a place around them. You're relying heavily on skeleton AI, that is not too good. When I was playing the Totem version, I would occasionally get screwed over by my skeletons choosing to wander off. Dark Pact will aim them, however they may not aim the boss, which means your damage wanders away from the boss, and while it does, you can not do anything.
Actual caster builds do have ways around this, such as Convocation, which recalls all of your minions to directly before you. However, the clunkiness of the method makes the build not worth it. Because there are minion assembles out there! This week, in fact, GGG showcased a much better one.
We've saved the best Pact construct for last. Dark Pact's self cast version is the strongest. No matter what situation you are in, this build is, without question, the most effective approach to use Pact. It is somewhat weak during leveling in which Dark Pact hurts you more than you're leeching, but it is significantly more harmful than another builds. That being said, the damage is times higher than either of those others.
Self-healing Dark Pact eliminates 6 percent of your max health every single cast. It also casts incredibly. Currentlymy level 80 character casts 5.8 times per second while buffed, and that is with no direct casting gear, so you'll be able to get yourself down to one health in around three minutes. Without amounts of leech, that is gont kill you dead. Fast. And this is why the Berserker course is indeed strong. They get an intrinsic 1 percent leech, as well as cheap poe currency each time they have a savage hit (15 percent of their health). This makes you immortal. Other courses can do so --Warlord's Mark and Atziri's Promise have an identical effect--but Berserker is definitely the simplest route.