Blue Conservatory Scroll
Drops from Instructor Tarahna. Sooo... why exactly does this one have a 1 hour cooldown, while the red and yellow scrolls only have 15 min cooldown?
The 
Blue Conservatory Scroll is a Legion toy that drops from the rare mob Instructor Tarahna in Mac'aree and applies a Blue Rune of Power buff that can be combined with other players' runes to create new colors.
Guide awaiting review
Find Instructor Tarahna
Travel to Mac'aree and locate the rare mob Instructor Tarahna at 61.4, 50.2. This rare is part of the Adventurer of Argus and Commander of Argus achievements, and has a chance to drop the Blue Conservatory Scroll upon defeat.
Use the scroll's buff
Using the Blue Conservatory Scroll applies a Blue Rune of Power buff with a 1-hour cooldown. Note that you cannot have more than one rune buff active at a time — using this scroll while another rune buff is active will remove the existing buff.
Combine runes with players
Walk over another player who has a different colored rune buff active to combine your runes: Blue combined with Yellow grants both players Green Rune of Power, and Blue combined with Red grants both players Purple Rune of Power. The combined buff lasts 10 minutes.
Tips
The combined rune buffs from mixing with another player last 10 minutes, longer than most individual scroll buffs.
Mixing already-combined colors such as Green, Orange, or Purple with other runes does not produce any further color combination.
