Hard to Kill is a Mythic Heroes feature that says:

Whenever you’re below 0 hit points, you automatically stabilize without needing to attempt a Constitution check. If you have an ability that allows you to act while below 0 hit points, you still lose hit points for taking actions, as specified by that ability. Bleed damage still causes you to lose hit points when below 0 hit points. In addition, you don’t die until your total number of negative hit points is equal to or greater than double your Constitution score.

At the same time Undead PC's have:

Undead have no Constitution score. Undead use their Charisma score in place of their Constitution score when calculating hit points, Fortitude saves, and any special ability that relies on Constitution (such as when calculating a breath weapon’s DC).

They also have:

Undead do not risk death from massive damage, but are immediately destroyed when reduced to 0 hit points or fewer.

Now my question is:

  • As an Undead PC do I get to use my Charisma instead of Constitution for Hard to Kill as per Constitution > Charisma replacement? Do I also move my instant death breakpoint from 0 to -2*Charisma Bonus?
  • \$\begingroup\$ There is only 1 legal kind of PC undead. Custom Race Builder Undead Type. Also Lich but since Lich can't die anyway it would make no sense in this context. \$\endgroup\$
    – Nec Xelos
    Commented May 27 at 8:21

1 Answer 1


RAW: It's pretty clear that an undead mythic creature is still destroyed when reduced to 0 or fewer HP. The Hard to Kill feature doesn't kick in until the creature is below 0 HP, and it only stabilizes such a creature; unfortunately, the undead creature is already destroyed.

Undead PCs use their CHA in place of CON "when calculating hit points", but they are still just as destroyed at 0 HP (or below) as a non-PC undead creature is.

So, sadly for your undead character, I think that RAW says you're still dead at 0 HP.

That said: this GM sees your proposal of using CHA instead of CON as reasonable and would be inclined to accept it. And, that said: having been running a mythic campaign for the past few years, I don't think that Hard to Kill has come up more than once between about level 10 and 20, and MR - through to 10.

  • 1
    \$\begingroup\$ Should the Specificity Priority rule kick in? Mythic Rule is more specific than Undead rule no? After all Charisma replacement works for "any special ability", not just HP calculation. \$\endgroup\$
    – Nec Xelos
    Commented May 27 at 8:22
  • \$\begingroup\$ @NecXelos: that's a reasonable argument in favor of the house rule, but I think that RAW still sees the undead destroyed at 0 or fewer HP. Compare undead's "destroyed" bit to disintegrate where "a creature reduced to 0 or fewer HP ... is entirely disintegrated". A mythic character reduced to -1 HP via disintegration would still be toast, even with Hard to Kill. The undead bit is the same: RAW doesn't say they die (since they're undead, dying is a weird concept for them), but that they're destroyed. \$\endgroup\$
    – minnmass
    Commented May 27 at 16:01

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