Rulings
Q1: What is the effect of "altering the original DP?"
This effect changes the original DP listed on the card to the number determined by the effect. For example, if a Digimon with an original DP of 8000 is selected with "MainUntil the end of the next opponent's turn, change the original DP of one Digimon in the opponent to 3000." If the Digimon is selected with "Main," the Digimon's original DP will be 3000 instead of 8000.
Q2: What happens if the DP of a Digimon with +1000 DP is changed by the "change original DP" effect?
The original DP is changed and +1000 is added to the value of the DP. The value being added is not included in the original DP.
Q3: What happens if the DP of a Digimon whose original DP has been changed by an effect is changed again by a "change original DP" effect?
It will be overwritten by the last changed value.
Q4: Can I change the DP of a Digimon that has no DP with the "change original DP" effect?
No, it cannot. An effect that changes information on a card cannot change information that the card did not originally have. For example, if Digimon, whose original DP is changed by an effect, becomes a card without DP by De-Digivolve, the DP of the card cannot be changed.
Data Sources
Lv.5 Mistymon BT18-039 U Ultimate | Virus | Magic Warrior/Witchelny <Barrier> [On Play] [When Digivolving] By trashing your top security card, change 1 Digimon's original DP to 6000 until the end of of your opponent's turn. --- Inherited: [All Turns] [Once Per Turn] When your security stack is removed from, this Digimon may unsuspend.
Lv.5 Mistymon BT18-039 U Ultimate | Virus | Magic Warrior/Witchelny <Barrier> [On Play] [When Digivolving] By trashing the top card of your security stack, change the original DP of 1 Digimon to 6000 until the end of your opponent's turn. --- Inherited: [All Turns] [Once Per Turn] When a card is removed from your security stack, unsuspend this Digimon.
Lv.5 ミスティモン BT18-039 U 完全体 | ウィルス種 | 魔法戦士型/ウィッチェルニー ≪防壁≫ 【登場時】【進化時】自分のセキュリティを上から1枚破棄することで、相手のターン終了まで、デジモン1体の元々のDPを6000に変更する。 --- Inherited: 【お互いのターン】[ターンに1回]自分のセキュリティが減ったとき、このデジモンをアクティブにできる。