When Tinybones Joins Up enters, any number of target players each discard a card.
Whenever a legendary creature you control enters, any number of target players each mill a card and lose 1 life.
It was going to be the greatest heist of his unlife.
When Tinybones Joins Up’s first ability resolves, the next target player in turn order (or, if it’s a target player’s turn, that player) chooses a card in hand without revealing it, then each other target player in turn order (if any) does the same. All chosen cards are then discarded at the same time.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.