Put the rest on the bottom of your library in a random order. While three or less might not sound like much, MTG is full to bursting with cards which only cost three mana or less that can win a game
Enter the Bargain, with twice the cost, only skips your draw step, you draw them immediately to cast them or in response to something, and it's even legal as a four of in Vintage where it used to be on the B&R list
Ive already blown my one affinity joke, so lets get into this
The play pattern here is to get Vivi in play, pitch a huge red spell card to cast a free Blazing Shoal and make Vivi enormous, then use Vivi's ability to generate loads of free mana and cast more giant spells, storm off, or simply swing and deal heaps of damage to your opponent with the now embiggened mage
Laboratory Maniac is not strictly worse than Thassa's Oracle, seeing as some combos require you to have this card in play and draw cards later