Hey all!
I think I have deciphered the underlying math of damages (about 90% of the tested monsters seem to use this to within 1 point).
Average Damage for any monster will equal:
5 (or d8) + 1/2 Level
Elites x2 damage
Solo Monsters x3 damage?
Minions possibly just deal the 1/2 level bit
Brutes possibly deal double damage on average.
Grick L7 Brute deals 2d6+4 +5 (Avg. 16), Average for a standard L7 might be 8 (5 + 3)
Grick Alpha L9 Brute deals 2d6+6 +5 (Avg. 18). Average for a standard L9 might be 9.
Skeletal Tomb Guardian L10 Elite AND Brute deals 1d8+6 (four attacks) Avg. 10 x 4 = 40. Average for a standard L10 might be 10.
A few monsters throw this 'rule' completely out the window, such as the War Devil.
It should be averaging about 32 damage (4d8+8 +5 ongoing or thereabouts).
The Phane should average approx. 36 damage as well. Instead it averages about half that. It may be some trade off for the insubstatial power, but it still seems very low.
The Pit Fiend does almost double its assumed damage average...
The Pit Fiend should average around 36 damage, and has 1d12+11 +5 fire (Avg. 22) and 1d6+11 +15 poison (Avg. 29) and Aura 15 Fire. So it averages 66.
Assuming the Tarrasque is a Level 30 Solo Brute(?) then it should be averaging around 120+ damage per round (and would have about 1800 hp).