Emperor Sem

Edison Card Text
Each time you Tribute Summon a monster, each player can select 1 card from their GY and return it to the top of their Deck.
Targets
Note: both parts of the effect
No Damage Step effect
Banlist • Unlimited
Rulings
edisonformat.net
●If you activate the effect of “Emperor Sem,” you need to return a card from your GY to the top of your Deck.
●Your opponent does not have to use its effect, but can do so if they wish.
●Each player targets 1 card in their GY for “Emperor Sem’s” effect.
●If you have at least 1 card in your GY, you can activate “Emperor Sem’s” effect even if your opponent has no cards in their GY.
●“Emperor Sem’s” effect starts a Chain. If an effect is chained that shifts control of the Tribute Summoned monster to your opponent, “Emperor Sem’s” effect resolves as normal. However, if control of “Emperor Sem” shifts to the opponent as part of the Chain, the effect of “Emperor Sem” is not applied because it is no longer a case where ‘you Tribute Summoned a monster’, as “you” now refers to your opponent.
edisonformat.com
If you activate the effect of “Emperor Sem,” you need to return a card from your Graveyard to the top of your Deck.
Your opponent does not have to use its effect, but can do so if they wish.
Each player targets 1 card in their Graveyard for “Emperor Sem’s” effect.
If you have at least 1 card in your Graveyard, you can activate “Emperor Sem’s” effect even if your opponent has no cards in their Graveyard.
“Emperor Sem’s” effect starts a Chain. If an effect is chained that shifts control of the Tribute Summoned monster to your opponent, “Emperor Sem’s” effect resolves as normal. However, if control of “Emperor Sem” shifts to the opponent as part of the Chain, the effect of “Emperor Sem” is not applied because it is no longer a case where ‘you Tribute Summoned a monster’, as “you” now refers to your opponent.