If this card is sent to the GY as material for a Fusion Summon: You can Special Summon 1 Fusion Monster from your Extra Deck in Defense Position (but negate its effects, also return it to the Extra Deck during the End Phase), also for the rest of this turn, you cannot Special Summon from the Extra Deck, except Fusion Monsters
Another exception for this stamp, is this Grey Thin stamp on a Shadowed Machamp (the only Shadowed card printed with a 1st edition stamp), which is from @scratchdesk 's collection
The reason why everyone isnt just running Seaking decks everywhere is that it only has a 50/50 chance of doing anything
Jill, Shiva's Dominant A decent enough tempo creature on her face, Jill bounces a nonland permanent, and eventually transforms into Shiva, Warden of Ice to let you get creatures through and disrupt your opponent some
Yes Man, Personal Securitron is some nice repeatable draw that also nets a treasure, and Seize the Spotlight will nearly always be a free draw three, because otherwise youre going to be getting value and treasures
Vanquish Soul Hollie Sue A consistency blow and a turn-zero check for Vanquish Soul