They come too late in the day to be useful, you would rather spend the mana on some action
Casting a spell with overload doesn't change that spell's mana cost
White cards include diarrhea, big butt cheeks filled with poop and barfing into a popcorn bucket, while the black cards ask things such as Where do babies come from? The Cards Against Humanity: Family Edition print-and-play is described as being a public beta of the upcoming board game, with the finished game planned for release this autumn
It counters un-counterable spells, stops triggers as small as Mulldrifter and as big as Emrakul, the Promised End, and can prevent the cascade of value that a player might still reap even if their spell is countered
To determine the total cost of a spell, start with the mana cost or alternative cost you're paying, add any cost increases, then apply any cost reductions
Don't worry its free