Vampiric Sands

Siphon health from a living creature to caster or caster transfers health to a living creature. 

Unwilling target creature makes a save against casters spell save DC. Upon failure target creature takes 1D6 plus spell modifier damage (necrotic). Damage rolled on the 1D6 is transferred to the caster as Health. On a successful save target creature takes damage halved. Halved 1D6 damage is still transferred to caster as Health. 

Willing creature can transfer Health up to their level plus 1D6. 

Caster can store up to the max number on the damage dice as temporary hit points until a short or long rest. 

If spell is dispelled a bonus action can be used to return sand to the casters control.