I forget exactly which game I first noticed this in, but I do know that in either PL or SL, if not both, there was an issue where having a combo elixir would actually give the enemies a buff as well. While you would still do massive damage to them, they would do massive damage to you as well, ignoring your defensive buffs. Sometimes it seemed like they even did more damage than usual.

While I have no direct proof or numbers to back this up, I believe the same is happening in DL WITH AND ONLY WITH the "all 3 buff combo." The rarest of the buffs, the one you want to get. It seems every time I get this 15 minute triple buff, I take the same amount of damage if not more damage from enemies.

This may just be my imagination, but I also have another theory as to where my blood is going. When you increase a skill to a new level, your damage goes up, but so does the amount of blood used. Is there a possibility that having a double damage buff could be effecting the amount of blood used per skill use? This would get rid of the above theory and make my missing blood be from only skill use (although I've watched the blood loss from damage and it still seems high for having a defensive buff). I haven't checked this yet, but will next time I get lucky.