I just had an idea when posting the pick below in the dragons thread. Bigger monsters need to do more damage. The DMG or MM (I can't remember which) gives guidance that as weapons in crease in size. Just give them another die. So a Large sword does 2d8 instead of 1d8 damage. I generally apply the same idea to my monsters. So if a Medium monster's tail does 1d8 damage (+ mod) then a Gargantuan should do 4d8 (+ mod) damage, right?

However, what if we increased the mod damage and the dice. So for each step up in size you add another mod. damage. So you would have 8 (1d8+4) damage for a Medium tail attack (STR 18) or 58 (4d8 +40) for a Gargantuan one. That seems better than what we get in the MM!

Red Dragon Tail: 19 (2d8 + 10) vs.

Improved Red Dragon Tail: 58 (4d8 +40)

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Here is an example I developed with these ideas later in the thread:

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