Blood Pact

Make a deal with a willing target allowing you to share HP. If this spell is used against an unwilling target, they must make a roll a DC Con saving throw against your spellcasting stat with advantage. When the spell is cast the caster decides which of the two HP options to use for the duration, be it the casters health or the targets. Damage done to any of the people effected by the spell goes to the same Hit-Points, but healing is only effective if applied to whomever the HP comes from( Ex. if a wizard and barbarian use this spell and they use the barbarians health, only health healed by the barbarian will work). Alliteratively, Temp HP is unaffected by this spell and will apply to the individual as usual.
Opposed to the usual 1 hour time limit, the pact will also end when the chosen HP hits 0, after which all effected targets including the caster must make their own saving throws to live.

Per every level above 7, one additional target may be added to the pact