“Chaos Emperor Dragon - Envoy of the End” sends itself to the Graveyard as part of its effect, and counts itself for determining how much damage it inflicts.
The damage that “Chaos Emperor Dragon - Envoy of the End” inflicts is equal to the number of cards BOTH players send to the Graveyard times 300 points.
“Barrel Behind the Door” and “Trap of Board Eraser” can be chained to “Chaos Emperor Dragon - Envoy of the End”’s effect. “Barrel Behind the Door” is, itself, sent to the Graveyard by “Chaos Emperor Dragon - Envoy of the End”’s effect and counts for an additional 300 points as a result.
If “Chaos Emperor Dragon - Envoy of the End” is destroyed or removed from play by an effect chained to its own effect, its effect still resolves.
Tokens will be removed from the field by “Chaos Emperor Dragon - Envoy of the End”’s effect, but will not add to the damage total because they are not sent to the Graveyard.
It is the controller, not the owner, of “Chaos Emperor Dragon - Envoy of the End” that can activate its effect and that inflicts damage to his/her opponent.
If you control your opponent’s “Chaos Emperor Dragon - Envoy of the End” and you pay the 1000 Life Points, the effect inflicts damage to your opponent even though the monster returns to your opponent’s Graveyard.
If “Chaos Emperor Dragon - Envoy of the End” is Special Summoned, and the controller immediately activates its effect, and the opponent chains “Torrential Tribute” as Step 2 of a chain, “Torrential Tribute” destroys all monsters on the field and sends them to the Graveyard, then “Chaos Emperor Dragon - Envoy of the End”’s effect resolves, sends all Spell & Trap Cards on the field to the Graveyard, and inflicts 300 points of damage to the opponent for each Spell & Trap Card sent to the Graveyard by its effect. (Monster Cards do not count toward the damage because they were destroyed and sent to the Graveyard in the middle of the chain by “Torrential Tribute”.)
If “Waboku” is chained to the effect of “Chaos Emperor Dragon - Envoy of the End”, it will not prevent the damage because “Waboku” only applies to Battle Damage. Also, “Waboku” will still be on the field when “Chaos Emperor Dragon - Envoy of the End”’s effect is applied, so it will still count for 300 points of damage to the opponent.
When “Minar” and “Electric Snake” are sent to the Graveyard by “Chaos Emperor Dragon - Envoy of the End”, their effects are not activated because the modified text on those cards says when they are “discarded to the Graveyard from the hand”.
Netrep Rulings:
“A Deal with Dark Ruler” may not be chained to the effect of “Chaos Emperor Dragon - Envoy of the End” if no Level 8 or higher monster has been sent to the Graveyard yet.
“Despair from the Dark” sent from the hand to the Graveyard by the effect of “Chaos Emperor Dragon - Envoy of the End” will be Special Summoned through its effect.
“Fake Trap” may not be activated in a chain with “Chaos Emperor Dragon - Envoy of the End’s” effect as the effect of “Chaos Emperor Dragon - Envoy of the End” does not destroy cards.
Netrep Q&As:
Q: Will the effect of “Gravekeeper’s Watcher” stop the effect of “Chaos Emperor Dragon – Envoy of the End”?
A: “Discard” and “Send” are not the same. You cannot use “Gravekeeper’s Watcher” against the effect of the Chaos Emperor Dragon. Curtis Schultz, 03/07/2004
Q: Can I chain “Super Rejuvenation” to “Chaos Emperor Dragon – Envoy of the End’”s effect and draw as many cards as Dragon Types discarded through “Chaos Emperor Dragon – Envoy of the End”’s effect?
A: “Super Rejuvenation” will not work with the effect of “Chaos Emperor Dragon - Envoy of the End.” “Super Rejuvenation” works for Dragon-Type monsters discarded from your hand or Tributed from your side of the field during the turn. “Chaos Emperor Dragon – Envoy of the End’s” effect does not Tribute any monsters. It does not discard any cards. Curtis Schultz, 03/10/2004