Currently sitting at 28 clears of Vesper's Host, still haven't got the exotic. I've met people who are near their 50th run, and they also don't have it. The top post while I'm writing this is from someone with 100 clears of Warlord's Ruin who doesn't have the Buried Bloodline exotic. I really want a pity system that would guarantee the exotic drops on the 20th clear or something like that.