Death Delayed

You delay the death a creature that will die and give them the strength to keep going for a little bit of time. You speak a sacred word, making the creature not die. That creature has 0 Hit Points, cannot re-die until this spell ends, ignores any damage taken, and is conscious for the full duration of the spell unless you fall unconscious, die, or if the creature becomes incapacitated. The creature does not need to make Death Saves, and can do whatever it pleases as if it were fully conscious and alive. While in combat, that creature has a +5 to hit, and deals an additional 3d10 damage whenever they deal damage. That creature scores a critical strike on a 19 or 20 on a d20, and roll a 19 or 20 on their roll on the d20, if the creature died to that attack, the spell ends, then the creature that has delayed death is set to 1 Hit Point, loses any failed or successful Death Saves, and will live as if it never died before the spell, but still dies if it were to die afterwords. A creature saved this way becomes marked. This mark cannot be removed unless by the DM. If you attempt to cast this spell on a creature already marked this way, you die, but the spell still triggers. If you die this way, you cannot cast the spell on yourself.