When this card on the field is destroyed and sent to the Graveyard, its Optional Trigger Effect activates. You must have at least 2 “Hydrogeddon” and 1 “Oxygeddon” in your Graveyard to target, otherwise the effect will not activate. If you have 3 correct targets, the opponent can chain “Disappear” to remove from play 1 of the monsters, but the other 2 will still be Special Summoned.
The effect of “Water Dragon” that activates when it is destroyed targets 2 “Hydrogeddon” and 1 “Oxygeddon” in the Graveyard.
If you do not have 3 open Monster Card Zones after “Water Dragon” is sent to the Graveyard, you cannot activate its effect.
If “Water Dragon” was face-down on the field when it was destroyed and sent to the Graveyard, you can still activate its effect.
Missing the Timing: If “Water Dragon” is destroyed by an effect in the middle of a chain, you will miss the timing and cannot Special Summon the 3 monsters from your Graveyard.
While “Water Dragon” is face-up on the field, either player can activate an effect to increase the ATK of a FIRE or Pyro-Type monster, but the Continuous Effect of “Water Dragon” will change it back to 0.