Name: Energy Rift
Circles: ?,?
Description: Cast on a single tile. Opens a rift to another plane, causing energy to flood out. Positive or negative energy can be chosen. All units in an army entering the area is either healed or damaged, depending on energy used and whether living or not. Average upkeep in mana.

To make a tile heal, we have Wellspring already.
As far as combining positive/negative in one spell... IIRC this idea has been shot down every time and split into 2 spells.
-1 from me.