Light and Darkness Dragon

Edison Card Text
① Cannot be Special Summoned.
② While face-up on the field, this card is also DARK.
③ Once per Chain, if a Spell/Trap Card, or Monster Effect is activated (Quick):
This card loses exactly 500 ATK/DEF and that activation is negated.
④ If this card is destroyed and sent to the GY: Target 1 monster in your GY (if possible); destroy all cards you control, also, after that, Special Summon that monster (if any).
Targets
Note: the first part of the last effect
No Damage Step effect
Banlist • Unlimited
Interactions
What happens if Light and Darkness Dragon negates Lyla's End Phase effect?✓
Lyla's mandatory End Phase mill effect activates, and Light and Darkness Dragon negates the activation.
Because Lyla's End Phase effect is a phase-dependent mandatory Trigger Effect, negating its activation causes it to activate again in the same End Phase. It will keep activating until Light and Darkness Dragon can no longer negate it because had lost its ATK/DEF.
If LaDD negates Stardust Dragon/Assault Mode's return, does it try again?✓
Stardust Dragon/Assault Mode attempts to return from the Graveyard.
It only attempts to return once. If that activation is negated, it remains in the Graveyard.
Rulings
edisonformat.net
● For the mandatory ③ effect to resolve, this card must be able to both negate the activation and also lose exactly 500 ATK and 500 DEF. If you can’t do either, you do neither.
● Vs Spirit Monsters, Lyla, Treeborn Frog, Vayu, etc:
These trigger effects will be negated by this card’s ③ effect, and can then trigger again.
(This can “loop” until Light and Darkness Dragon can’t lose any more ATK/DEF.)
● Summoning a monster with the ④ happens after cards are destroyed.
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