Zartai Zartanai, the Ruthless

When Zartai Zartanai, the Ruthless enters the
battlefield, each opponent rolls a D20 and
creates X artifact bell tokens, where X is the
number they rolled. At the beginning of their
upkeep, opponents sacrifice one bell token.
When Zartai Zartanai attacks a player with 0
bell tokens, he gains shadow until end of turn.
{2}{p/b}: Target opponent sacrifices 1 bell token.