OK, so this is my attempt at a monster template. As we know, dragons are classified into 5 age catagories (wrymling, young, adult, ancient). This effort is intended to add the "mature" dragon right betwen the young, and the adult.
My goal here was create a dragon at a lower challenge rating, that still had access to legendary actions, though not all the legendary abilities, and maybe provide a more gradual reprsentaton of a dragon as it grows into it's power. I really tried to make this simple enough and generic enough to lay right over the top of an existing young dragon to quickly create a "mature" dragon.
So, check it out and by all means, share any feedback. Let me know what you think, is this something you would use? I think I'm most curious to see if you thing my Challenge Rating adjustment is enough. Most dragons appeared to have a 7 point spread in the challenge rating between the young and the adult, so I tried to go for half that amount rounded down (thus a +3 to the challenge rating). Check it out...
Mature Dragon Template
Size: Large (this is a mature dragon, and though it may be a bit bigger than a young dragon, it's not reached the adult size yet)
AC: Use the young dragons AC
Hit Points: Add 1/2 the static HP bonus rounded down to the HP total. Example, a young black dragon has +45 HPs (divided by 2 = 22), for an additiona 22 HPs for a mature black dragon
Attribute Adjustments (make the following adjustments to the young dragons attributes)
Str +2
Dex No Adjustment
Con +2
Int +1
Wis +1
Cha +1
Saving Throws: Add 1/2 of the specified save attribute, rounded down. Example: a young black dragon has a +6 Con saving throw (so 6 divided by 2 = 3), for a Con save of +9 for a mature dragon
Skills: Use the young dragons skills as printed
Senses: Use the youngs senses (blindsight, darkvision)
Challenge: Add +3 to the young dragons challenge rating to get the challenge rating for the mature version
Attacks: Add +2 to the young dragons attacks
Damage: Add +1 to the young dragons damage
Breath DC: Add + 2 to the DC of the young dragons breath weapon
Breath Damage Use the young dragons damage
Tail Attack: Subtract -2 from the adults dragons tail attack and damage
Legndary Actions: A mature dragon gains the legendary actions of the adult (however, subtract 2 from the save DC and damage of the wing attack)
A mature dragon does not gain legendary resistance or frightful presence
No love for my mature dragon build 
Heck, even distain would be something, lol. Is this a decent idea? Pulling access to legendary action down to a cr 10 dragon a bad idea? Neat idea? Anything?
I thought 4 age categories was a little light myself. Without the MM in hand, I can't really offer any critique on what you wrote, but I like the idea. Heck, why not add in an 'old' category between Adult and Ancient?
akr71 wrote: