You must follow the normal timing permissions and restrictions of the Goblin spells you cast from your library.
Conspicuous Snoop
If an activated ability of Goblin card on top of your library references the card it's printed on by name, treat Conspicuous Snoop's instance of that ability as though it referenced Conspicuous Snoop by name instead. For instance, if Conspicuous Snoop has Brash Taunter's ability, Conspicuous Snoop fights, not Brash Taunter.
If the top card of your library changes while you're casting a spell, playing a land, or activating an ability, you don't reveal the new top card until you finish doing so. This means that if you cast the top card of your library, you can't look at the next one until you're done paying for that spell. While the top card isn't revealed, Conspicuous Snoop doesn't have any abilities of that card.
Magic: The Gathering · ™ & © Wizards of the Coast · Illus. Zoltan Boros
Card data via Scryfall. Rarix is fan-made; not endorsed by the rights holders.
