My Spell Masteries for POTD
Wizard
1st: Slicken. Huge aoe with reflex based knockdown? Yes, please!
2nd:Miasma of Dull Mindness. Extremely crippling debuff.
3rd: Minor Blights. Amazing damage, will last for the entire fight.
4th: Confusion. Life Saver, foe only, decent area.
Druid:
1st: Tanglefoot. Instant cast, huge area, hobble is an amazing debuff, especially when most druid spells target reflex which is the weakest enemy save even on POTD. Great synergy with Slicken. If you go with two druids, then have the other master Sunbeam. Awesome range, damage and blind for a very long duration. What's not to love?
2nd:Autumn's Decay. Good area, amazing damage for a level 2 spell. The cone is rather easy to get off against knocked down enemies or the ones being held at chokepoints by your tank.
3rd: Twin Stones. Great damage, huge area, foe only. Perfect.
4th: Calling the World's Maw. Great damage, huge area, knockdown. Gotta love knockdown.
Priest:
1st: Blessing. More accuracy and damage are always nice.
2nd: Supress Affliction. Even if you have a paladin, one more way of stopping afflictions can be very useful, especially since you can use it as party wide.
3rd: Dire Blessing. More crits = more fun. Instant cast time is great!
4th:Devotions for the Faithful. Great buff AND debuff all in a single spell with good duration to boot! Shining Beacon can be nice but I find the super short range rather awful, especially since my priests don't wear armor.