So I tested out untamed regen and it may be one of the most useful feat skills that are available to bear Shaman. A basic over view of the skill is that it grants the priest an ability which increases their rate of life regeneration but increases the damage inflicted by enemy attacks. It is an instant cast and stays on until you click it off. So if you play smart this skill will be your best friend. Often when bear Shaman Are soloing stamina is the only problem. so far I haven't had any trouble with maintaining mana except while i am the only healer in a group killing elites they do alot of damage and with steady hots its pretty difficult to heal through it all considering you have one decent size heal that is on a 30 second cooldown.
+137.8 natural mana regen
+46.4 natural health regen
+91.8 natural stamina Regen
-10% to all invulnerability's
So basically while you have this buff up you do not have to worry about mana or stamina but you do take more damage. So you have to be smart while using this skill if you are fighting Mobs that hit hard and you are the one taking the damage I wouldn't advise using this skill until after the fight to regen fast. But however if you are fighting mobs that dont hit to hard or you are in a party healing or assisting with damage keep the buff up and you wont have much trouble with stam and mana.