Sirius, the Brightest One

Vigilance, First strike.
Whenever Sirius, the Brightest One attacks, you
may pay {x}{w}. If you do, create X 1/1 white
Celestial Soldier creature tokens with first strike that
are tapped and attacking. Sacrifice this tokens at the
beginning of the next end step.

Whenever a player expend 4 during their turn,
reveal the top card of that player library. Other
creatures you control gain protection from colors in
that card until end of turn.