Drakkar, turncoat soldier

If you control two Human soldiers, this card gets
+1/+0 and Vigilance.
If you control three Human soldiers,this card gets
+1/+1 and Vigilance.
If you control four Human soldiers,this card gets
+2/+1 and Vigilance.
If you control five or more Human soldiers,
this card gets +2/+2 and Vigilance and
Double strike.