Pep, Raucous Raider is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Trample, Haste Whenever a creature you control deals combat damage to a player, exile the top card of that player's library. It perpetually becomes an artifact if it's a nonland permanent card. Until end of turn, you may play the exiled card. , Sacrifice an artifact: Add three mana of any one color.