This what I have used while trying to level
#showtooltip Arcane Shot
/targetenemy [noharm]
/castsequence [harm] reset=target Hunter’s Mark, null
/castsequence reset=target Serpent Sting, Arcane Shot, Arcane Shot, Arcane Shot
/cast !Auto Shot
/petattack
No need for GSE just make a macro and use it as is