Relay Soul

Per-phrase breakdown

• Special Summon 1 monster from your hand. (Effect)
• While it is face-up on your field, you take no damage. (Lingering)
• When it leaves the field, your opponent wins the Duel. (Condition)

Judge-facing facts

• Normal Trap Card
• Special Summons 1 monster from the hand
• Applies a continuous effect preventing you from taking damage while the monster is face-up on your field
• Applies a win condition for the opponent when the monster leaves the field

Card-specific notes from database

• Cannot be activated during the Damage Step (Konami neuron)
• While the damage prevention applies, monsters are still destroyed by battle normally (Konami neuron)
• If the Special Summoned monster is flipped face-down or becomes an Xyz Material, the damage prevention and win condition stop applying permanently (Konami neuron)
• The opponent winning the Duel does not start a Chain Link (Konami neuron)
• If the monster is moved to the Spell & Trap Zone without leaving the field (e.g., equipped, placed in Pendulum Zone), the damage prevention stops applying. If that card later leaves the field, the opponent will not win the Duel (YGOResources)
• If the monster is destroyed and placed in the Spell & Trap Zone (e.g., Crystal Beast), it is treated as leaving the field first, so the opponent wins the Duel (YGOResources)