1.Nf3 f6 2.Nd4 Nh6 3.e3 c6

White has several options here:

4.Nc3 Ng5 (or 4...d6 5.Nb5 cxb5 6.Bb5 Nc6 7.Qh5 g6 8.Qd5 d6 9.Qxd6),

4.Nb5 Ng4 5.f4,

4.Qh5+ g6 5.Nb5.