Thunder King Rai-Oh

Per-phrase breakdown

• Neither player can add cards from their Deck to their hand except by drawing them. (Continuous)
• When your opponent would Special Summon exactly 1 monster (Quick Effect): You can send this face-up card to the GY; negate the Special Summon, and if you do, destroy it. (Quick)

Judge-facing facts

• Normal Summon / Set from hand uses no tributes (Level 4).
• The effect preventing players from adding cards from the Deck to the hand except by drawing is a Continuous Effect.
• The effect to negate a Special Summon is a Quick Effect that activates in the Monster Zone.
• Sending this face-up card to the Graveyard is the cost to activate the Quick Effect.
• This Quick Effect does not target.
• This Quick Effect can only be activated in response to a Special Summon that does not start a Chain (e.g., Synchro, Xyz, Pendulum, Link Summons, or inherent Special Summons).

Card-specific notes from database

• (YGOResources) You cannot activate cards that mandatorily add a card from the Deck to the hand at resolution (e.g., Primite Imperial Tomb) while this card's effect is applying.
• (YGOResources) You can activate cards that optionally add a card from the Deck to the hand at resolution (e.g., Fire Formation - Tenki), but you cannot apply the effect to add a card if this card's effect is still applying at resolution.
• (YGOResources) You cannot activate the effect to negate a Special Summon if the Special Summon is performed by a card effect that treats the Special Summon as a Synchro, Xyz, or Link Summon.
• (YGOResources) If you attempt to Special Summon a monster to your opponent's field (e.g., Lava Golem), your opponent can activate the effect of Thunder King Rai-Oh to negate that Special Summon. If negated, any restrictions applied by that Summon (such as being unable to Normal Summon/Set) are not applied.
• (Konami neuron) The effect to negate a Special Summon can be activated when a monster is Synchro, Xyz, Pendulum, or Link Summoned immediately after the resolution of a card effect, provided that effect was activated as Chain Link 1. It cannot be activated if the effect was activated as Chain Link 2 or higher.
• (Konami neuron) While this card's effect is applying, you can activate Lullaby of Obedience; if the declared monster is found, the opponent must choose to Special Summon it to your field (they cannot choose to add it to the hand).
• (Konami neuron) You can activate Gold Sarcophagus while this card's effect is applying, because adding a banished card to the hand is not considered adding a card from the Deck.