Dominus Purge — Ruling

Regola generale

Regarding『if your opponent controls a card, you can activate this card from your hand:』
This is not treated as an effect.
In addition to activating this card normally while it is Set, if there is at least one card on your opponent's field, you can also activate this card from your hand by placing it face-up in a Spell & Trap Zone.
You can activate this card this way during either player's turn.

About this card's ① st effect:
If an effect (of a Spell, Trap, or monster) is activated, and that activation includes an effect to add a card from your Deck to your hand, this card can be activated on the Chain Link immediately following that activation.
You cannot activate it during the Damage Step.
When this effect resolves, the previous Chain Link's effect will be negated. (Even if that Chain Link's effect includes other things besides "adding a card from the Deck to the hand", since the Chain Link's effect is negated, that entire effect will not be applied.)
When this effect resolves,『negate that effect.』If there is a Trap in your Graveyard, you must then apply『destroy that negated card.』Additionally, if this card was activated from the hand,『you cannot activate DARK, WATER, or FIRE monsters' effects for the rest of this Duel』is then also applied to you.
Even if you have already activated a DARK, WATER, or FIRE monster effect during this Duel, you can still activate this card from your hand.『You cannot activate DARK, WATER, or FIRE monsters' effects for the rest of this Duel』is applied as part of this effect's resolution, and applies from that point going forward.