When "Advanced Heraldry Art" is activated, after Special Summoning the 2 targeted monsters with its effect, an Xyz Summon using those 2 Special Summoned monsters is performed immediatly. Therefore, if the effect of "Summon Limit" is being applied, "Advanced Heraldry Art" cannot be activated during a turn in which a Normal Summon has already been performed. Also, if "Advanced Heraldry Art" is activated during a turn in which a Normal Summon has been performed and "Summon Limit" is chained, the effect of "Advanced Heraldry Art" that Special Summons the 2 targeted monsters does resolve, but the effect that performs an Xyz Summon using the 2 Summoned monsters doesn't resolve. The same goes for seal of orichakcos since you cannot summon a monster from your extra deck you cannot activate the Advanced Heraldry Art and if the Stygian Dirge is already activate and you dont have an XYZ with the correct rank you cannot activate the Advanced Heraldry Art but if it was chained to the activation of the Heraldy art then the heraldy art resolves as much as possible.