Black Knife Ringleader

Shadow, deathtouch

Pay 3 life: Target creature gains shadow and becomes an Assassin in addition to its other types until end of turn.
Any player may activate this ability.

Whenever one or more Assassins deals combat damage to a player, that player creates half X treasure tokens rounded down and draws half X cards rounded down.
Whenever a player loses the game, each player creates X treasure tokens and draws X cards.
X is the number of Assassins on the battlefield.