About Priests, it goes from extreme to extreme, this cooperates next to useless in TBC, but now in Wrath of the Lich King Classic, it will be a must to have one priest class.
Preventing or absorbing damage before Boss bites a part of character's HP pool is what they excel at, so everyone want to prioritize a Discipline Priest for their raids. Their cheap flash shields is going to be less effective for example in dungeons, but in dungeons damage is not that great, they are still needed even though their spells are costing a lot of mana. They also have nice replenishment for mana from talents and abilities, such as Hymn of Hope and all-time popular Shadowfiend. With more and more intellect, Discipline Priest becomes quite self-sustained and can carry out fights without any worries. On top of that it has two awesome cooldowns, one which resembles Hysteria from DK, but does not stack with Bloodlust, and other one for naughty dps who over aggro.
Holy Priests, the healing class of TBC just carrying both aoe healing and single target, but now in WOTLK it just falls behind new Resto Druids and improved Holy Paladins a little bit. It still has the potential and really strong cooldowns, even Lightwell is kinda viable now. The holy priest strong side is its weakness at the same time, being able to cover any type of healing needed and working synergy with other healers makes, holy priest good at everything but not strongest in anything. Raid healing with Prayer of Mending, Prayer of Healing and Circle of Healing is great, but mana intensive.
Shadow Priest found a new power in the form of new spells, like Mind Sear for example. Shadow Priests will be quite decent dps throughout the entire expansion from start to the end, and it's going to make some of us main shadow priest players in TBC quite happy. The DoT ability, which is huge since the vast majority of shadow priest damage comes from DoTs. With the AOE ability and the multi DoTs, you get really strong caster dps that has some awesome utility in form of debuffs on target. DoTs can be stacked in great composition to boost overall dps, heals while doing damage. It's overall really fun to play with changing and interesting rotation, which is modified by stats and gear you have.
Can I see a lot of players playing priests? I'd say about the same amount as now, maybe a tad bit more as shadow priests since it will have a nice output at the beginning, but healing specs of it won't be stacked and will count at least one, either holy or discipline. Overall in what look, priest is not a bad choice if you are into this things.
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