"Flashback [cost]" means "You may cast this card from your graveyard by paying [cost] rather than paying its mana cost" and "If the flashback cost was paid, exile this card instead of putting it anywhere else any time it would leave the stack." You must still follow any timing restrictions and permissions, including those based on the card's type
Shopkeeper's Bane
Example: Magical Labyrinth for example is an Equip Spell that can normally only be equipped to Labyrinth Wall and allows you to Tribute the equipped monster to special summon Wall Shadow. In this instead, the card types are Monsters so you can equip Magical Labyrinth to any Monster you control and Tribute it to special summon any other Monster from your deck using the effect of Magical Labyrinth. Note: Monster Types arent considered as specific names, so Dragon Capture Jar would still only affect dragon type monsters.
Lastly, theres Bristly Bill, who spits out counters like crazy with its landfall ability
As Wizards itself admits, the term 'proxy' can sometimes be used colloquially for either
After all, Frodos quest may have failed without the assistance of Aragorn, Eowyn, and the rest of the Kingdoms of Men