A big part of what keeps this fair is that Mana Leak is missing a lot of things by the point in the game Mystic Confluence is getting cast
Newer titles have moved away from the paradigm of the heroes of light collecting the scattered crystals in favor of broader, more convoluted plot-lines, but most games in the series still have a crystalline element somewhere
Planeswalker - Chandra
Weve got avenues for Eldrazi tribal, artifact synergy, Pestilence effect decks, and the list goes on
Stormchaser's Talent is one such Class: If it exits and then returns to play, you'll get a second 1/1 blue Otter token, and if it gained a level before being exiled it will be reset, and you'll be able to use the second ability to fetch an instant or sorcery from your graveyard a second time
Corrupt Corrupts a simple payoff for being mono-black (or running Urborg, Tomb of Yawgmoth) that often ends games