Progressive spells use special mechanics that put 'hidden' spells on your character at level 250, and it's those spells that get triggered when you use the base ability.
A script on the base spell item gives you these hidden spells as well as the base spell. If you just get them from /spellscribe, the hidden spells won't get applied and the base spell won't have anything to trigger. As of 11/6, the scroll/tome items should give you the hidden spells.
How you get them
These will be sold on a vendor (name/location to be determined) in the Burning Lands expansion. In that form, they will give you the hidden spells you qualify for.
How you make them better
The spells are tied to your progression through the expansion. You'll be able to cast at least the first rank just for buying it, but getting the best rank will require raiding.
Each rank of these spells is tied to an achievement, and earning that achievement will grant you an item to use to upgrade your spells.
When you get what
Rank 1 - No requirements, just buy it
Rank 2 - Complete Adventurer of the Burning Lands (Group) OR Complete the Plane of Health achievement in the Broken Mirror (old rank 5).
Rank 3 - Complete Vindicator of The Burning Lands (Group) OR Complete access to Crypt of Sul (old rank 6).
Rank 4 - Complete Heatseeker (Group).
Rank 5 - Complete access to request one of the second tier raids (Achievement: Winds of Ash (Raid)).
Rank 6 - Complete access to request one of the third tier raids (Achievement: Flameward (Raid)).
|Scroll: Dissident Blessing||2998pp 2gp 3sp 8cp|
|Scroll: Dissident Companion||2979pp 2gp 3sp 3cp|
|Scroll: Dissident Fang||3002pp 9gp 2sp 4cp|
|Scroll: Dissident Fire||2994pp 5gp 4cp|
|Scroll: Dissident Force||2974pp 2gp 1sp 6cp|
|Scroll: Dissident Fury||3028pp 2gp 3sp 7cp|
|Scroll: Dissident Fusillade||2995pp 6gp 4sp 8cp|
|Scroll: Dissident Paroxysm||2994pp 3gp 6sp 6cp|
|Scroll: Dissident Psalm||3031pp 5gp 4sp 9cp|
|Scroll: Dissident Reinforcement||3026pp 2gp 7sp 9cp|
|Scroll: Dissident Roar||3010pp 2gp 2sp 1cp|
|Scroll: Dissident Winds||2988pp 8gp 6sp 2cp|
|Tome: Dissident Form||2994pp 3gp 6sp 6cp|
|Tome: Dissident Rage||2969pp 4gp 1cp|
|Tome: Dissident Shield||2997pp 8gp 4sp 9cp|
|Tome: Dissident Weapons||3032pp 5gp 2cp|