"A massive orc force is gathering at the gates of Zzaion."
"Orc reinforcements have arrived at the gates of Zzaion! The gates are under heavy attack!"
"More orc reinforcements have arrived at the gates of Zzaion! The gates are under heavy attack!"
"The gates to Zzaion have been breached! Orcs are invading the city!" After this warning Zzaion gate opens
"More orcs have arrived in Zzaion! The city is under attack! Strong lizard leaders have come to defend the city." Immediately after this message expect bosses to appear!
There's a 10 minutes gap between 3rd and 4th warning, and between 4th and 5th, so you have some time to pack healing and mana potions. You will need them!