(1) A person eighteen years of age or older is guilty of the crime of assault of a child in the second degree if the child is under the age of thirteen and the person:

(a) Commits the crime of assault in the second degree, as defined in RCW 9A.36.021, against a child; or

(b) Intentionally assaults the child and causes bodily harm that is greater than transient physical pain or minor temporary marks, and the person has previously engaged in a pattern or practice either of (i) assaulting the child which has resulted in bodily harm that is greater than transient pain or minor temporary marks, or (ii) causing the child physical pain or agony that is equivalent to that produced by torture.

(2) Assault of a child in the second degree is a class B felony.