Hulk has the following ability:
While Hulk is active, whenever either you or Hulk takes damage, Hulk deals 2 damage to each opposing character (no matter how many Hulks are fielded).* He deals 3 damage instead.
If Hulk blocks a character with Overcrush, would Hulk ability occur twice (once for hulk taking damage, and once for the opponent taking damage)?
For instance, Level 1 Hulk Green Goliath (6 Atk/5 Def) blocks Level 3 Martian Manhunter Green Martian (7 Atk/4 Def) with Overcrush. Does Hulk to 3 damage or 6 damage to all opposing characters?
No. When a card’s ability is triggered multiple times by the same, simultaneous game effect, the card’s ability only triggers once. Here, there is a single game effect (the attacking Martian Manhunter’s attack damage) which resolves simultaneously. As a result, a card ability triggered by that game effect (Hulk) only triggers once. In your example, Hulk would only deal 3 damage to opposing characters.
Some people have been confused about what constitutes multiple game effects. A second copy of Martian Manhunter, dealing damage directly to the player, would be an additional game effect.
The relevant text from the rulebook and FAQ is as follows:
DC Dice Masters: Justice League Rulebook Page 10:
Both players assign damage. Damage occurs simultaneously.
DC Dice Masters: Justice League Rulebook Page 26:
Overcrush: When attacking, if this character knocks out all of its blockers, it deals any leftover damage to your opponent.
Marvel Dice Masters FAQ – 9/22/2014:
13) Q: If a card effect is triggered multiple times by the same game effect, does the card effect happen multiple times as a result?
No, just once.
-The Dice Masters Rules Team