Until end of turn, you may play the card you own exiled this way and each other card exiled this way with lesser mana value than it without paying their mana costs
For example, if you control Laughing Jasper Flint and Vial Smasher, Gleeful Grenadier, having a creature an opponent owns that normally isn't an outlaw enter the battlefield under your control will cause Vial Smasher's ability to trigger
A modal double-faced card can be transformed or be put onto the battlefield transformed
Death Toll decklist for Duskmourn Commander Giving Deathtouch to Winter, Cynical Opportunist provides stability while you put together graveyard combos and take advantage of the MTG Delirium mechanic
It reminds me of Wizards of the Coasts older Commander precons, which were often more like two or three half-decks in a trenchcoat (the idea being that players would play a few games, get a feel for which mechanics they liked and then start swapping in cards to emphasize that part of the deck)
There are so many great ETBs these days, so youll often just be buying something back in addition to bouncing another creature and drawing a card