Rulings
Q1: Does this card's digivolution requirement where it can digivolve from a Tamer mean that the Tamer that will become a digivolution card is treated as a Digimon when it digivolves?
No, it digivolves from the Tamer as-is.
Q2: When a Tamer would digivolve using this card's digivolution requirement, is it considered a Digimon that would digivolve?
No, it isn't considered a Digimon that would digivolve. When a Tamer would digivolve using this card's digivolution requirement, "when a Digimon would digivolve" effects don't trigger.
Q3: When a Tamer digivolves using this card's digivolution requirement, is it considered a Digimon that digivolves?
No, it isn't considered a Digimon that digivolves. When a Tamer digivolves using this card's digivolution requirement, "when a Digimon digivolves" effects don't trigger.
Data Sources
Lv.4 Sephirothmon BT18-066 C Hybrid | Variable | Mutant [Digivolve] [Mercurymon]: Cost 1 [On Play] [When Digivolving] By placing 1 level 4 or lower [Hybrid] trait card other than [Sephirothmon] from your hand or trash as this Digimon's bottom digivolution card, you may activate 1 [On Play] effect on the placed card as an effect of this Digimon. --- Inherited: [Opponent's Turn] This Digimon gets +2000 DP.
Lv.4 Sephirothmon BT18-066 C Hybrid | Variable | Mutant [Digivolve] [Mercurymon]: Cost 1 [On Play] [When Digivolving] By placing 1 level 4 or lower [Hybrid] trait card other than [Sephirothmon] from your hand or trash as this Digimon's bottom digivolution card, you may activate 1 [On Play] effect on the placed card as an effect of this Digimon. --- Inherited: [Opponent's Turn] This Digimon gets +2000 DP.
Lv.4 Sephirothmon BT18-066 C Hybrid | Variable | Mutant [Digivolve] [Mercurymon]: Cost 1 [On Play] [When Digivolving] By placing 1 level 4 or lower card with the [Hybrid] trait other than [Sephirothmon] from your hand or trash as this Digimon's bottom digivolution card, you may activate 1 [On Play] effect on the placed card as an effect of this Digimon. --- Inherited: [Opponent's Turn] This Digimon gets +2000 DP.
Lv.4 セフィロトモン BT18-066 C ハイブリッド体 | ヴァリアブル種 | 突然変異型 「メルキューレモン」:コスト1 【登場時】【進化時】自分の手札/トラッシュから、「セフィロトモン」以外の特徴に「ハイブリッド体」を持つLv.4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、置いたカードの【登場時】効果1つをこのデジモンの効果として発揮できる。 --- Inherited: 【相手のターン】このデジモンをDP+2000。