You don't have to do anything when the effect activates if you have 3 or more cards in your security stack
Metagame Breakdown 89 Nekroz (56 Nekroz, 31 Deskbot Nekroz, 1 Atlantean Nekroz, 1 Herald Nekroz) 84 Shaddoll (687 Shaddoll, 16 Artifact Shaddoll ) 55 Qliphort 37 Atlantean (26 Atlantean, 10 Atlantean Mermail, 1 Artifact Atlantean) 28 HERO 15 Evilswarm 13 Tellarknight 8 Train 6 Dragon Ruler 4 Dragon Ruler Hieratic 4 Volcanic (3 Volcanic, 1 Artifact Volcanic) 4 Yosenju 3 Infernoid 3 Yang Zing 2 Ritual Beast 2 Bujin 2 Infernity 2 Prophecy 1 Artifact Chronomaly 1 Blackwing 1 Chain Burn 1 Cyber Dragon 1 Six Samurai Nekroz The limitation of Manju of the Ten Thousand Hands and Senju of the Thousand Hands saw Nekroz fill in with Mathematician
On the other hand, Rosenkreuz, played by Seto, appears and makes an offer to the hero to join his side, the Yorkists
If you do this to an Extra Deck Monster, it gets sent back to the Extra Deck and your opponent has to get it out again