Rulings
Q1: What does this card's "while this card is revealed from your deck, this card is also treated as level 6" mean, exactly?
This effect means that this card is also treated as a level 6 card while it's flipped over from the deck by a "reveal cards from the deck" effect. If the effect is an effect such as "add 1 level 6 Digimon card from the revealed cards," you can use that effect to add this card to the hand.
Q2: If I reveal 2 copies of this card using BT3-051 Dokugumon's On Play effect, can I add both copies to my hand?
Yes, you can. The effect reads "also treated as level 6," therefore this card can be treated as both level 5 and level 6, so you can add 2 copies to your hand.
Q3: Does the "if deleted by an effect" effect activate when this Digimon's DP becomes 0 and is deleted due to a DP-reducing effect?
No, it doesn’t activate. This Digimon is deleted by the rules, not the DP-reducing effect. Therefore, it doesn't meet the "if deleted by an effect" condition.
Q4: What cards does "level 5 or lower card with Dark Masters in its text" in this card's inherited effect refer to?
This effect targets a level 5 or lower card with Dark Masters in its text from your trash. This card's inherited effect has been changed to "When Attacking Once Per Turn By placing 1 level 5 or lower card with Dark Masters in its text from your trash as this Digimon's bottom digivolution card, this Digimon gets +2000 DP for the turn." Please see the notices regarding changes to the rules/rulings on the official website.
Data Sources
Lv.5 Mephistomon BT17-068 C Ultimate | Virus | Fallen Angel While this card is revealed from your deck, this card is also treated as level 6. When this card would be played from the hand, by returning 1 [Apocalymon] from your trash to the bottom of the deck, reduce the play cost by 3. [On Deletion] If deleted by an effect, you may play 1 [Gulfmon] or 1 level 6 [Dark Masters] trait Digimon card from your hand or trash without paying the cost. --- Inherited: [When Attacking] [Once Per Turn] By placing 1 level 5 or lower card with [Dark Masters] in its text from your trash as this Digimon's bottom digivolution card, this Digimon gets +2000 DP for the turn.
Lv.5 Mephistomon BT17-068 C Ultimate | Virus | Fallen Angel While this card is revealed from your deck, this card is also treated as level 6. When this card would be played from the hand, by returning 1 [Apocalymon] from your trash to the bottom of the deck, reduce the play cost by 3. [On Deletion] If deleted by an effect, you may play 1 [Gulfmon] or 1 level 6 [Dark Masters] trait Digimon card from your hand or trash without paying the cost. --- Inherited: [When Attacking] [Once Per Turn] By placing 1 level 5 or lower card with [Dark Masters] in its text from your trash as this Digimon's bottom digivolution card, this Digimon gets +2000 DP for the turn.
Lv.5 Mephistomon BT17-068 C Ultimate | Virus | Fallen Angel While this card is revealed from your deck, this card is also treated as level 6. When this card would be played from the hand, by returning 1 [Apocalymon] from your trash to the bottom of the deck, reduce the play cost by 3. [On Deletion] If deleted by an effect, you may play 1 [Gulfmon] or 1 level 6 Digimon with the [Dark Masters] trait from your hand or trash without paying the cost. --- Inherited: [When Attacking] [Once Per Turn] By placing 1 level 5 or lower card with [Dark Masters] in its text from your trash as this Digimon's bottom digivolution card, this Digimon gets +2000 DP for the turn.
Lv.5 メフィスモン BT17-068 C 完全体 | ウィルス種 | 堕天使型 このカードがデッキからオープンされている間、このカードはLv.6としても扱う。 手札のこのカードを登場させるとき、自分のトラッシュから、「アポカリモン」1枚をデッキの下に戻すことで、支払う登場コスト-3。 【消滅時】効果で消滅していたなら、自分の手札/トラッシュから、「ガルフモン」か特徴に「ダークマスターズ」を持つLv.6のデジモンカード1枚をコストを支払わずに登場できる。 --- Inherited: 【アタック時】[ターンに1回]自分のトラッシュから、特徴に「ダークマスターズ」の記述があるLv.5以下のカード1枚をこのデジモンの進化元の下に置くことで、ターン終了まで、このデジモンをDP+2000。