Here is the first of the weekly dragons for the month of July, the thunder dragon. First the M20 statblock:

Adult Thunder: HD 18d12+72 (189), AC 27, Bite +22 (2d6+7), or Breath 6d6 sonic DC 23, phys+DEX to dodge for half. STR 23, DEX 10, MIND 10. Phys 5, Subt 8, Knowledge 5, Communication 5

And now for the Basic Fantasy Statblock

Dragon, Thunder

Armor Class: 18
Hit Dice: 6***
No. of Attacks: 2 claws/1 bite or breath/1 tail
Damage: 1d4/1d4/2d8 or breath/1d4
Movement: 30' Fly 60' (20')
No. Appearing: 1, Wild 1, Lair 1d4
Save As: Fighter: 6 (as Hit Dice)
Morale: 9
Treasure Type: H
XP: 665

Thunder dragons are about the size of white dragons, but more stocky in build. They are slow fliers that prefer to move along the ground. They are light brown and distinctively marked with large, irregularly-shaped, blood-red-edged ellipses. When first seen, sages called them clouded dragons.

Thunder Dragons prefer to live in large caverns in mountains or hilly areas. Over time, they continue to enlarge their home cavern into a byzantine maze. They are considered by other dragons as more brute than intelligent dragon. As a result, thunder dragons tend to be neutral in outlook, and generally distrustful of other dragons.

Thunder dragons prefer to fight by means of a sophisticated ambush that best uses their sonic breath weapon and chameleon-like abilities. They are motivated to reproduce and accumulate treasure. They prefer a diet of vegetables and rocks, but they are not adverse to eating the occasional mountain lion or dwarf.

Thunder dragons use a sonic breath weapon. This blast of sound disorients target creatures, leaving them effectively stunned for 1d4 rounds. No attack roll is required, but a save vs. Death Ray is allowed to resist. They also have the ability to blend into their surroundings like a chameleon, allowing them to surprise prey on 1-3 on 1d6.

Thunder dragons are immune to sonic attacks.

Thunder Dragon Age Table

Age Category

1

2

3

4

5

6

7
Hit Dice

3

4

5

6

7

8

9
Attack Bonus

+4

+5

+6

+7

+8

+9

+10

Breath Weapon Sound (Line)
Length

-

60'

70'

80'

85'

90'

95'
Width

-

25'

30'

30'

35'

40'

45'
Chance/Talking

0%

15%

20%

30%

45%

55%

65%
Spells by Level

Level 1

-

1

2

3

3

3

3
Level 2

-

-

-

-

1

2

3
Level 3

-

-

-

-

-

-

1
Claw

1d4

1d4

1d4

1d4

1d4

1d6

1d8
Bite

2d4

2d6

2d6

2d8

2d8

2d10

2d10
Tail

1d4

1d4

1d4

1d4

1d4

1d6

1d6