

Q1: What does this card's All Turns effect do, exactly?
This effect triggers and can be activated when a Digimon specified by it leaves the battle area under the specified conditions. When activated, all Digimon matching its trigger conditions are prevented from leaving.
Q2: In what order do a Security effect, "when ... performs a security check" effect, and "when a card is removed from ... security stack" effect activate when they trigger simultaneously upon a security check?
Security effects take precedence for activation. Upon a security check, a Security effect will immediately activate without pending activation. For other triggered effects, the turn player activates their effects first.
Lv.4 Dimetromon BT24-012 U Champion | Virus | Reptile/LIBERATOR <Blocker> [All Turns] When any of your other Digimon with the [Reptile] or [Dragonkin] trait would leave the battle area by your opponent's effects, by returning this Digimon to the hand, they don't leave. --- [Your Turn] [Once Per Turn] When your opponent's security stack is removed from, gain 1 memory.
Lv.4 Dimetromon BT24-012 U Champion | Virus | Reptile/LIBERATOR <Blocker> [All Turns] When any of your other Digimon with the [Reptile] or [Dragonkin] trait would leave the battle area by your opponent's effects, by returning this Digimon to the hand, they don't leave. --- [Your Turn] [Once Per Turn] When your opponent's security stack is removed from, gain 1 memory.
Lv.4 Dimetromon BT24-012 U champion | Virus | Reptile/LIBERATOR <Blocker> [All Turns] When any of your other Digimon with the [Reptile] or [Dragonkin] trait would leave the battle area by your opponent's effects, by returning this Digimon to the hand, they don't leave. --- [Your Turn] [Once Per Turn] When your opponent's security stack is removed from, gain 1 memory.
Lv.4 ディメトロモン BT24-012 U 成熟期 | ウィルス種 | 爬虫類型/リベレイター ≪ブロッカー≫ 【お互いのターン】特徴に「爬虫類型」/「竜人型」を持つ他の自分のデジモンが相手の効果でバトルエリアを離れるとき、このデジモンを手札に戻すことで、離れない。 --- 【自分のターン】[ターンに1回]相手のセキュリティが減ったとき、メモリー+1。