you can tribute 1 "MechTech" monster you control, Summon 1 "MechTech Dragon Corrupted", "MechTech Knight Corrupted", or "MechTech Defender Corrupted" monster from your Deck or hand with the same Level as the tributed monster
Soul-Guide Lantern, first printed in Theros Beyond Death , last seen in Phyrexia: All Will Be One Commander
Unfortunately for Doctor Kaiba, Yugi's ultimate trump card is an apple
All of these are SWSH Black Star promos and included with them is the standard Professor Burnet Black Star Promo card that came with all the previous V-UNION boxes
However, Charizard ex also has the same issue and of course, its nothing that a Rare Candy card cant assist with
The curse, is that if Relay Soul leaves the field, your opponent will win the duel