I've developed an unique play style for Slark Suport Disruptor where you sole purpose is to "nullify" enemies spells and engages: Put yourself in the front, cast Q, try some attacks to stack, wait until Q is almost ending, escape with W or an item, get back and regen with ULT then repeat again. You will be surprise by how many times you'll do this against 5 enemy heroes and still be alive. Best played vs spells that are dispellable, not good vs any mana burn. If you manage to stay alive long enough, you'll stack a lot of essence shift, along side with being very tanky and the item build you could carry side by side with your carry.