The game is very simple. Take the previous card, and make some "minor" modification(s) to it so that it is still balanced.
This can mean: adding or removing an ability, altering card type, changing cost, or really about anything as long as you don't change too much about the card in a single post.
Try not to get too Un-, since the card ought to remain rules viable, and try not to get too overpowered.
The extent of the "minor" modifications is very subjective... but there must be a clear connection to the previous card.
Starting from (my) last post in MTGS:
Group Knowledge
Sorcery
Join forces - Starting with you, each player may pay any amount of mana. Each player draws X cards, then returns a card with converted mana cost X or less from their graveyard to their hand, where X is the total amount of mana paid this way.
