Because shock lands have land types (Plains, Island, Swamp, Mountain, Forest), they are searchable with fetch lands, forming a powerful mana-fixing duo
In order to be able to do this the sacrifice ability really needs to have no mana cost and be unconditional
When you do, exile target creature an opponent controls until Shire Shirriff leaves the battlefield
It came to MTG Arena on April 28, 2022 just one day before the global tabletop release on April 29
It is also interesting that holos with gray stamps seem to only be thin stamps, and Machamp only seems to have a gray stamp with the shadowed version
With this in mind, its little wonder that Sire of Seven Deaths is currently the third most expensive card in MTG Foundations