Pain Domain

Pain is a reality of mortal existence, and different deities throughout the pantheon strive to cause or prevent mortal pain. Some who worship these deities take up this divine mission. 

Clerics of the pain domain run the range of alignments: from those who seek to prevent and alleviate the pain of others, often bearing it themselves, to those who serve evil gods bend on mortal torment, delighting in torturing and mortal suffering. Whatever their goal, pain clerics remind the world of the inevitability of suffering and often make others uneasy, even when their services are welcome. 

Bonus Proficiency

Your dedication to pain has blessed you with knowledge of anatomy and understanding the causes and prevention of pain. You gain expertise at the Medicine skill, adding double your proficiency bonus to checks with that skill.

Disciple of Pain

When a creature you can see within 30 ft of you takes damage from a hostile creature, you can use your reaction to transfer that damage to yourself (after applying resistance or other such modifiers), which becomes an equal amount of psychic damage.  Damage so taken does not interfere with your Concentration. When you take damage using this reaction, you can regain a spell slot equal to 1/10th of the damage taken before resistance or other reductions are applied (round up, minimum of 1 and maximum of your highest spell level). You may use this reaction a number of times equal to your proficiency bonus, regaining all expended uses on a long rest.

Channel Divinity: Alter Suffering

Starting at 2nd level, you can use your Channel Divinity to enhance suffering or healing. 

As a bonus action, you empower your ability to cause or alleviate pain. The next time you deal necrotic, radiant, or psychic damage, or heal a creature before the end of your next turn, you may select a number of targets equal to half your proficiency bonus (round down), and instead of rolling damage or healing for those targets, they instead receive the maximum possible damage or healing. You roll damage or healing for remaining targets as normal.

Master of Suffering

Beginning at 6th level, your devotion to pain grants you certain benefits. You gain resistance to psychic damage. When you cast a cleric spell that deals radiant or necrotic damage, you can choose to have it deal psychic damage instead.

Divine Strike

 Once on each of your turns when you hit a creature with a weapon attack or deal damage with a cleric cantrip, you can cause the attack to deal an extra 1d8 psychic damage, increasing to 2d8 at 14th level. 

Sustain Life

Your power over pain reaches its zenith, granting you the divine power to prevent mortal blows. When a creature you can see within 30 ft of you, including yourself, suffers damage that would reduce them to zero hit points or kill them outright, you can use your reaction to have them be reduced to one hit point instead, or to be reduced to zero hit points and instantly stabilized (your choice). You can use this reaction a number of times equal to your proficiency bonus, regaining all uses on a long rest.