Train the Townsfolk

Whenever a Human enters the battlefield under
your control, you may create a colorless Trap
artifact token with "{t}, Sacrifice this artifact: Tap target creature."
{2}{w}: Humans you control get +1/+1 till the end
of turn.
"There is no length that humanity won't go to, to defend their home."
-Alena, Trapper of Kessig