Cheery Barter

Each player exiles the top four cards of his
or her library. Starting with you, each player may offer to exchange one of the permanent cards he or she exiled this way for a permanent card exiled this way by another player. If the offer is accepted, put those cards onto the battlefield, then their owners exchange control of them.
"Ah, there's the spirit! Be nice, all and sundry, or none will have ought to do with you!"
- Inre, Table-Runner