Which cards [...] get?

What are you even using this deck for, bosses? If so, throw a kanna for % boss dmg like DA, and a hayato helps for min crit % dmg. Other than that, eh, you have a well enough deck set. Although I don't even know if you guys have them. Sacrifice gives a buff? What the...

We don't have them (yet?).
The buff refers to post-red Sacrifice where it allows me to spam Gungnir.

But when it comes to the other sets, why are you ignoring mercedes aran and evan combo? Sure its not much healing on Aran/Evan but its still something. Mercedes cooldown reduction will be sorta helpful for the new death factor for berserk (dont know for sure if this works) and for consuming beholder. You also get some nice 7 all stat that works with potential from having 3 hero classes, which is by far a better choice over phantom night lord and xenon when only xenon card is the useful one in those 3.

I haven't even considered that because Aran and Evan cards are pretty much useless (I already have a consistent hp drain and mp consumption does not require recharging without potions). Mercedes card only reduces cooldown by 3% up to max 5 seconds, which on a grand total of 480s of Reincarnation is pretty negligible. So I would rather directly complete a resistance set, which gives the +7 allstat same as hero set, but includes also DA's 3%boss card.

if you're playing DrK, for red (and even if not) you'll most probably want a mech card, buff duration is a VERY NICE thing, gives you more of a window to rebuff, and if it affects our reincarnation/sacrifice time, it also adds some SERIOUS damage.

Yes, I'm playing a DrK as main and I accounted the 15% buff card already.

I might consider making a paladin/buccaneer for the "level to physical damage" (taken from here), though I don't know how they work, can anyone explain?