Class Hall tree seems up, if not working yet.
So we have
I: Arcane Provenance - Doubles the chance for your quest rewards to get a rare or epic Bonus Upgrade.[NYI]
Frost Nova - Increase success chance against Minions by 20% on the first mission of the day.
II: Blink - Reduce mission duration of all missions by 30%.
Arcane Library - Increase the maximum number of Apprentices and Conjurors you can recruit from 2 to 4.
III: Elemental Power - Newly recruited Water Elementals become Arcane Golems, which add: Quickening - Increases success chance of missions by 30% when accompanied by Arcane mages.
Higher Learning - Newly recruited Apprentices become Conjurers, which add: Presence of Mind - Increased mission success chance by 30% when a Spell is present.
IV: Teleportation Nexus - World teleport unlock.[NYI]
Refreshment Table - Reduces the cost of recruiting all troops by 25%.
V: Might of Dalaran - Daily nuke WQ. [NYI]
Arcane Armaments - You can place a work order for Champion armaments once a day. [NYI]
VI: Legends of Ragnarok - Upgrades your artifact forge to allow socketing of a third relic slot. [NYI]