International Ragnarök Online Chaos: Wave Mode - Sky Instance on Ranger

Can you prevent the monster waves from reaching the other side for 1 hour? This instance has different rules compared to Forest instance. -Unlike monsters in Forest , these monsters here DO attack and hit quite a lot, however it can be deadly if mobbed. All monsters here are aggressive. All monsters here are Holy type as well so it's best to bring dark/shadow element weapon. -In Sky mode, you will have 3 mercenaries that will help you to attack the incoming monster wave but they will die if they reached the monster spawn area. -In Forest mode, monster waves loop every 70 waves, while in Sky mode, monster waves loop every 10 waves. -Treasure boxes appear every 5th wave. Amount of boxes spawning goes up by 1 for every succeeding 5 waves until it reach 5 boxes which it will remain 5 boxes spawned from wave #25 onwards. Treasure boxes contain STR/INT/AGI/VIT +6 food (heavy weight) that lasts for 20 minutes, as well as Yggdrasil berry and some stones used to enchant mid/low headgear costumes. Warning! DO NOT let the mercenaries kill the treasure boxes, otherwise the boxes will be empty! -All monsters do not drop anything except treasure boxes. All monsters do not give experience as well. -The Instance will be over once 20 monsters managed to get to the other side or 1 hour has passed.