I think health funnel has some potential as a healer spell so why not have a Re that allow it to be cast on player:
Health transfer (name subject to change if a better is found )
first part: Health funnel become health transfer and can also be cast on party member (raid member and all kind of pet too) the more healing power the more health is transferred ( you heal more but take more damage).
second part: As health transfer is active 50% of the healing you receive will be transferred to your target instead of you. transferred life doesn’t work with AOE healing spell and is not affected by your healing power as this will be too op.
The balancing of this spell is of course needed, and the number can be tweaked, but you can see the picture.
I think that having a way to have a shadow or warlock type of healer that use his life to heal can be an original new way to play and this is a first RE that can go toward this