I'm playing a mostly stock precon, with an added Tifa LockhartTifa Lockhart and Firion, Wild Rose WarriorFirion, Wild Rose Warrior
You don't even need Mamoswine to be your Active Pokemon to use this ability
Second, it is in artifact so opens this effect up to artifact synergy decks that would not care about Trial of Ambition
Booting up the game for the first time and seeing the "NEW GAME" and "Continue?" options in the black void with JUST the Buster Sword stabbed into the ground is beyond iconic
While you may have to jump through significant hoops to reanimate a monster, even just recurring a utility creature like Eternal WitnessEternal Witness or Sakura-Tribe ElderSakura-Tribe Elder gets you additional sacrifice fodder and some value/card advantage of top of that
Restricted Office // Lecture Hall gives you that option, and its a good thing for aggro decks that are low to the ground