The player with the highest number loses half their life rounded up, while the player with the lowest number discards that many cards
It's probably a bunch of RTR bulk and the seller is trying to "get their money back." (there seems to be a common misconception among people selling their cards on Craigslist that their cards should be worth at least as much as the boosters they opened to get the cards)
This allows phasing cards to keep counters, auras, and equipment attached to them when they phase back in
If you do, target opponent loses 2 life unless that player sacrifices a permanent or discards a card
Card draw doubling cards are not a common theme or strategy, but they provide players with a great way to gain card advantage
Creature - Demon Berserker Demonlord Belzenlok Flying, trample When Demonlord Belzenlok enters, exile cards from the top of your library until you exile a nonland card, then put that card into your hand