Q1: How many Machinedramon cards can I place under this card when I DigiXros it?
1 card. Unless specified otherwise, you can only place 1 of each of the cards shown in the DigiXros requirements.
Q2: Does "cards from your trash may also be placed for this card's DigiXros" mean that I can place cards from my hand, battle area, and/or trash for the DigiXros?
Yes, that's correct. In addition to Digimon from the hand or battle area, you may also place cards from the trash for the DigiXros.
Lv.6 Chaosdramon BT17-057 U Mega | Virus | Machine/SoC [Digivolve] Lv.5 w/[SoC] trait: Cost 3 While you have a black Tamer, cards from your trash may also be placed for this card's DigiXros. [On Play] [When Digivolving] By placing 1 [Cyborg] or [SoC] trait card from your trash as this Digimon's bottom digivolution card, delete up to 7 play cost's total worth of your opponent's Digimon. [All Turns] When this Digimon would leave the battle area by an opponent's effect, by trashing 2 [Cyborg], [Machine] or [SoC] trait cards in its digivolution cards, prevent it from leaving. DigiXros -2: [Machinedramon]×1 Lv.5 Digimon card w/[Cyborg] trait
Lv.6 Chaosdramon BT17-057 U Mega | Virus | Machine/SoC [Digivolve] Lv.5 w/[SoC] trait: Cost 3 While you have a black Tamer, cards from your trash may also be placed for this card's DigiXros. [On Play] [When Digivolving] By placing 1 [Cyborg] or [SoC] trait card from your trash as this Digimon's bottom digivolution card, delete up to 7 play cost's total worth of your opponent's Digimon. [All Turns] When this Digimon would leave the battle area by an opponent's effect, by trashing 2 [Cyborg], [Machine] or [SoC] trait cards in its digivolution cards, prevent it from leaving. DigiXros -2: [Machinedramon]×1 Lv.5 Digimon card w/[Cyborg] trait
Lv.6 Chaosdramon BT17-057 U Mega | Virus | Machine/SoC [Digivolve] Lv.5 w/[SoC] trait: Cost 3 While you have a black Tamer, cards from your trash may also be placed for this card's DigiXros. [On Play] [When Digivolving] By placing 1 [Cyborg] or [SoC] trait card from your trash as this Digimon's bottom digivolution card, delete up to 7 play cost's total worth of your opponent's Digimon. [All Turns] When this Digimon would leave the battle area by an opponent's effect, by trashing 2 [Cyborg], [Machine] or [SoC] trait cards in its digivolution cards, prevent it from leaving. DigiXros -2: [Machinedramon] x 1 Lv.5 Digimon card w/[Cyborg] trait
Lv.6 カオスドラモン BT17-057 U 究極体 | ウィルス種 | マシーン型/SoC 特徴に「SoC」を持つLv.5:コスト3 黒の自分のテイマーがいる間、このカードのデジクロスで自分のトラッシュのカードも置ける。 【登場時】【進化時】自分のトラッシュから、特徴に「サイボーグ型」/「SoC」を持つカード1枚をこのデジモンの進化元の下に置くことで、登場コスト合計7まで、相手のデジモンを消滅させる。 【お互いのターン】このデジモンが相手の効果でバトルエリアを離れるとき、このデジモンの進化元から、特徴に「サイボーグ型」/「マシーン型」/「SoC」を持つカード2枚を破棄することで、離れない。 「ムゲンドラモン」×特徴に「サイボーグ型」を持つLv.5のデジモンカード1枚