My first deck ever was a mono-black lifegain deck with pieces like Zulaport Cutthroat, Xathrid Necromancer, and Necropolis Regent
So if a creature with 1/1 printed on the normal side and 2/3 printed on the flipped side has a +1/+1 counter on it, it changes from a 2/2 to a 3/4
"The List" in MTG: A curated list of older cards reprinted with their original art and set symbol, but with a tiny Planeswalker symbol in the bottom-left corner
Counter Intelligence/World Shaper - Edge of Eternities OK, Im cheating a little here, but both Edge of Eternities decks were great
Conversely, when you cast Prosperity for X=4, you lose a card (Prosperity itself), but you gain four cards, for a net gain of three
Tergrid, God of Fright This broken five-drop lady on the Game Changers list has menace and then a discard and sac trigger for your foe when they do a permanent