Breath of Doom is a Permanent Evolution that says:
If you attack Tokyo, deal 1 damage to all other Monsters not in Tokyo.
Mecha Blast is a Temporary Evolution that says:
Discard this Evolution to deal 2 extra damage.
Claws of Steel is a Permanent Evolution that says:
Deal one extra damage on a turn in which you dealt 3 or more damage.
Starting with some poorly worded terms, Damage means: Lose [Heart]. It is unclear if Claws of Steel could be used in a 4 player game when Meka Dragon is in Tokyo and rolls a single [Claw] (since you are dealing 1 damage to 3 Monsters), or if it requires dealing 3 damage to a single source. I believe the correct answer is the latter.
Can you reveal all three of these Evolutions during a turn where you attack Tokyo with a single [Claw], and if you do, what is the result?
(Example: Do you deal 1 damage to Tokyo and with Breath of Doom 1 damage to all other Monsters, discard Mecha Blast to deal 2 more damage to Tokyo and all other Monsters, and Claws of Steel makes all Monsters take an additional 1 damage. Final Result: 4 damage to all other Monsters, or does the additional 2 damage from Mecha Blast not hit the Monsters outside of Tokyo?)