EA mantle already applies fire/light a few times. In addition Holy presence fully heals all nearby targets, so applies
Heal, a level 6 cleric spell to an unlimited number of nearby allies, so is essentially auto-casting
Mass Heal, the most powerful cleric spell, a level 9 spell with extended cast time, automatically with no cast time or cost every 6 seconds.
The correct balance for Holy Presence would be for it to apply
Close Wounds a level 2 cleric spell, randomly to one nearby ally, since it is already also already applying fire/light level 2 damage spells. For it to be passive, we make it the weaker level 2 cleric healing spell. Automatically applying close wounds when soloing would do 13 healing x 8 (spell power 700) * 3 (200 AMP) * 1.7 (crit) = 530 points of healing on tick would be fair and balanced.