The "you" in "on your side of the field" is the current controller’s field, so as long as "Horus the Black Flame Dragon LV 4" is face-up, it is always "face-up on your side of the field".

If "Horus the Black Flame Dragon LV 4" destroys a monster, you can activate its effect during the End Phase, even if the destroyed monster was your monster that was controlled by your opponent.

If you don’t have "Horus the Black Flame Dragon LV6" in your hand or Deck, you cannot send "Horus the Black Flame Dragon LV4" to the Graveyard to activate its effect.

If "Horus the Black Flame Dragon LV 4" destroys a monster as a result of battle, and is removed from play by "Interdimensional Matter Transporter", and returns to play during the End Phase, you can still activate"If Banisher of the Light" is in play, you cannot send "Horus the Black Flame Dragon LV 4" to the Graveyard, so you cannot activate its effect.

You don’t have to send "Horus the Black Flame Dragon LV 4" to the Graveyard if you don’t want to, even if it destroyed a monster as a result of battle. But if you activate its effect by sending it to the Graveyard, you must Special Summon "Horus the Black Flame Dragon LV 6" if possible.

You can activate the effect of "Horus the Black Flame Dragon LV 4" during your opponent’s End Phase if appropriate.

If a level monster fulfills its condition to Special Summon the next-highest level (for example, if "Armed Dragon LV5" destroys a monster as a result of battle), and the level monster is then flipped face-down, or removed from play permanently, or sent to the Graveyard and then Special Summoned from the Graveyard, then its condition is reset and it is no longer considered to have met the condition to level up to the next level.

Horus' Servant: "Horus' Servant" has an effect just like "Lord of D.", but only applicable to "Horus the Black Flame Dragon". "Horus' Servant" will not negate a card effect. All it does is prevent "Horus the Black Flame Dragon" from being selected as a target. If your opponent selects "Horus the Black Flame Dragon" as a target (with "Ring of Destruction", for example), and you chain "Call of the Haunted" to Special Summon "Horus' Servant", then "Horus the Black Flame Dragon" will still be destroyed by "Ring of Destruction" because "Horus' Servant" is being Special Summoned AFTER "Horus the Black Flame Dragon" was selected. The fact that "Ring of Destruction" has not yet resolved does not matter; "Horus the Black Flame Dragon" was selected at the activation of "Ring of Destruction", and "Horus' Servant" is Special Summoned too late to prevent this.

Horus' Servant: Your opponent cannot activate a Spell Card, Trap Card, or Monster Effect that would select "Horus the Black Flame Dragon" as a target while "Horus' Servant" is in play. "Horus' Servant" does not cause the effect to be negated; he prevents the activation of the effect in the first place.

Serial Spell: You cannot Level Up "Horus the Black Flame Dragon" from 4 to 8 with just "Level Up!" and "Serial Spell". Because you would send "LV4" to the Graveyard for "Level Up!", but even if you copy it with "Serial Spell", the first "Level Up!" hasn't resolved, so "LV6" isn't on the field to send to the Graveyard as a cost for the copy of "Level Up!" If you have "Horus the Black Flame Dragon LV4" and "Armed Dragon LV3" on the field, and send one of them to the Graveyard with "Level Up!", you cannot use "Serial Spell" to Level Up the other monster, since there was no monster sent to the Graveyard as a cost for "Serial Spell", and "Serial Spell" would have no point of reference to resolve its effect.


LV Monster Rulings
{{:Card Rulings:LV