Healers in AoC don't select a target and heal just that target, nor do they automatically heal everyone in their group. Rather, they heal all friendly targets standing in a 120 degree cone of effect in front of them. We'll call those spells "CoE heals." The Priest of Mitra will get bonuses to his or her damage output based on how many friendlies he or she has healed recently. He or she will have an ability called "Reciprocal Healing" that will allow him or her to AoE heal friendlies when affected by a CoE heal from another healer -- making groups with multiple priest-types particularly potent.
Perhaps most impressively, the Priest of Mitra will have access to a wide and dynamic range of crowd control spells by level 80 -- including "stun, fear, knockback, snare, and blind abilities." All that and more in the interview. Check it out.