Transfer Heal

This is a very dangerous way of healing and should be avoided unless there is no other choice. It works in 2 phases and needs 2 rounds before the spell finishes taking effect.
NOTE: creature that takes damage is called "the donor" and creature chosen to be healed is called "the target".

Phase 1:
Use dice (or DM) to decide the random creature that shall become the donor. This is any creature, including yourself within range that isn't the target. Choose also the target (unlike with the donor, this is a voluntary choice).
Call out the donor's name followed with the target's name. Example: I henceforth sacrifice John to heal Jack.
The donor needs to roll a constitution save against spell DC to determine if they become paralysed for till the end of the spell.

Phase 2:
Your eyes turn blank as you use your strongest available attack to hit the donor. If your attack is successful, all damage sustained by the donor during the last round will be transferred as a surge of positive energy washes through the target, causing it to regain all the damage hit points the donor sustained. The target is no longer unconscious if they where. This spell has no effect on constructs or undead.

The spell fails if your attack fails, the target leaves your attack range or you lose concentration. All damage sustained by the donor during the entire duration of the spell will be the amount of hit points you lose in necrotic damage. If it's specifically concentration, it's only half of that damage and the target will regain that half in hit points.