Spam stealth, ambush

/run local _, _, active = GetShapeshiftFormInfo(1) if not active then CastShapeshiftForm(1)end
/run CastSpellByName("Ambush")

Ambush / Backstab

If stealthed cast Ambush, else cast Backstab

/run if (string.find(GetShapeshiftFormInfo(1), "Invis" )) then CastSpellByName("Ambush") else CastSpellByName("Backstab"); end

Ambush / Eviscerate / Backstab

/run if GetBonusBarOffset() == 1 then CastSpellByName("Ambush") elseif GetComboPoints()>=3 then CastSpellByName("Eviscerate") else CastSpellByName("Backstab")end