It appears based on the below tooltips that DRG's AoE combo extends Blood of the Dragon TWICE, but not Disembowel's +10% damage buff. This seems like an oversight considering MNK's and SAM's AoE combos extend Shifu/Jinpu, and Greased Lightning/Twin Snakes buffs respectively. What this means is, during our AoE rotation, we would need to interrupt our AoE attacks to do True Thrust->Disembowel for the buff and then return to our 3-part AoE combos. Compared to MNK and SAM who don't need to do this, it seems sort of unfair or potentially overlooked.
https://i.imgur.com/bsuUyJz.png
https://i.imgur.com/QhnREYj.png
https://i.imgur.com/xxKPm4J.png
