At Death's Door

For 1 hour, you must continuously recite the prayer used as a componet for this spell, wich begs the entity from wich you draw your magic for their blessing in order to stave off Death itself. During the same hour, you also must constantly channel the spell's power towards a willing creature within range, remaining uninterrupted for the entire ritual(if your concentration fails, the spell imediatly fails and the spell slot used is wasted). 

For the next 8 hours after this process, the creature infused with this spells's energy gains a limited form of immortality. The next time they hit 0 hit points, they do not fall unconscious or roll death saves, their body and mind fueled by the called-upon entity's own power. Instead, they remain conscious, and are able to take actions and resolve their turns normaly. 

However, for every time they take damage from any source during this state and until they next regain hit points, be it by class features, magic, or resting, they must roll a d100. If the roll is 68 or higher, the creature is moved closer towards Death's embrace, as the magic begins to fail, and they mark a failed death saving throw, dying as normal should they rack up 3 fails. 

Whenever the target creature regains hit points after benefiting from this spell's effects, the spell ends, and they are immediatly afflicted with all the weight of having such a close encounter with Death. For the next 8 hours, they have a -3 penalty to all their attack rolls and saving throws(except death saving throws), a -2 penalty to their initiative rolls and AC, a -5 modifier to all their damage rolls, and suffer from a level of exhaustion, all of wich can't be removed except for a period of 1d4 days of rest and light activity. 

AT HIGHER LEVELS

When you cast this spell using a spell slot higher than 7th level, the number they most roll lower than in a d100 to not mark a failed death saving trow increases, with that being 79 for an 8th level spell slot, and 88 for a 9th level spell slot.