Noelle, Knight of the Crystal

First strike, vigilance
Whenever Noelle attacks, you may pay {x}{w}. If
you do, create X 1/1 white Soldier creature tokens
that are tapped and attacking.
{2}{w}: Until end of turn, Noelle gets +X/+X,
where X is the number of Knights you control.
Whenever Noelle or another Knight you control
enters the battlefield under your control, you gain
1 life.