Damage: This is the damage budget for all the monster’s attacks. Limited-use (daily, recharge, or situational) attacks do 4x the damage budgeted. Multi-target attacks do ½ the damage budgeted. Limited-use multi-target attacks do 2x. All other damage sources are 1 for 1, including at-will and legendary single-target attacks, auras, reactions, and variable-length effects like Swallow. If a monster has several at-will options (such as melee and ranged), the lower-damage options are free.
The example stat block that the author uses to illustrate these rules involves a low-level creature that can only make a single attack per round, and in this situation the rules seem to work out. I'm having more trouble figuring out how the rules work when you start throwing multiattack into the mix or when you get into the higher levels with powerful creatures that have legendary actions, for instance.
The Monster Manual lists the Adult Red Dragon as a CR 17 creature. According to the blog's rules, this would give it a damage budget of 85. The dragon's fire breath is a limited-use, multi-target attack that deals an average of 63 points of damage to those who fail their saves, so as per the rules this should use up 31 out of the 85 budget, leaving 54.
The legendary Wing Attack also falls into this category and so should use up 7 more of the budget, leaving 47.
The blog's rules indicate that only the most powerful at-will attack, which is a 1 for 1 on the budget cost, requires any budget, which means that the Bite attack eats up the 26 of the remaining budget, leaving 21.
Is this correct? Does the fact that the dragon has multiattack come into play in the budget calculations? Or is it that the dragon is a powerful creature and thus based on "concept" it should be up to 50% higher on the damage budget? In this case, we're looking at a budget of up to 127, and then it seems like accounting for every attack available works out: 31 for the breath weapon, 7 for the wing attack, 26 for the bite, 15 x 2 for the claws, 17 for the tail, for a total of 111.