Edison format ruling
Sillva, Warlord of Dark World

Card effect (current official text)If this card is discarded to the Graveyard by a card effect: Special Summon it from the Graveyard, then, if this card was discarded from your hand to your Graveyard by an opponent's card effect, your opponent returns exactly 2 cards from their hand to the bottom of their Deck, in any order.
Rulings
Also see rulings for "Dark World Monsters".
- If this card is discarded from your hand by the opponent’s card effect, and they only have 1 card in their hand, then you still can Special Summon "Sillva, Warlord of Dark World", but the other part of the effect will not resolve because the opponent does not have 2 cards to select.
- "Sillva, Warlord of Dark World" must be Special Summoned to resolve the second part of his effect. If you cannot Summon him because you activated "Scapegoat" that turn, or your Monster Card Zones are full, then the second part of his effect does not resolve.
- If the Special Summon of "Sillva, Warlord of Dark World" is negated with "Royal Oppression", the second part of his effect does not resolve.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Edison forum — sourced change requests get reviewed.