Ok so EDH will give you even more fun with your response to #5. EDH is now known as commander though. What it is, 100 card deck, singleton rules(meaning no duplicates of cards except basic lands), and one of the cards is a legendary creature you use as your general(you can have more than one legendary creature in your deck). The deck can only have cards with color identity of the legendary creature you're using as your general, so if you chose a legendary creature with black and blue in its mana cost, your deck can only have black, blue, and colorless mana cost spells. This goes for abilities as well. So say I has a blue/black EDH and wanted to put the card Bump in the night(cost one black. Sorccery. Target opponent loses 3 life. Flashback 5 colorless and a red), it can't be used because it also has red in it.
One great thing about this format, everything not on a very small ban lost is legal(although unglued and unhinged sets are always illegal). So you can pull off crazy *** combos and other fun stuff I'm EDH. EDH is also 3 players or more so it gives you time to set things up. I have one combo in a deck that is an instant win infinite loop combo.
The legendary creature you choose as your general gets to start in its own zone called the general zone. You can cast that creature from this zone as if it was from your hand. If your general is killed, you choose to put it in the graveyard or back in the general zone with a general tax. For each tax on the general, it adds 2 colorless to the mana cost of the creature.
Players have 40 life instead of 20, and can only take 21 from generals or they lose.