"Using this weakness is the only way to solo the Rogue." Aiden's thoughts moved fast, and he quickly came up with a plan. When fighting a snake, go for its weak spot. Against a slow-attacking mage, the best way was to predict the skill and counter it. Of course, that was easier said than done. Except for certain special cases, a boss' skill casting in Doomsday was completely random. There was no pattern at all. Predicting when a boss would cast a skill required very sharp judgment. Bosses at this level were deadly. Once they cast a skill, the player basically had no chance to survive. Even Aiden was no exception. "Gray, don't use any skills on your own. Wait for my command." Aiden watched the Rogue closely as a faint Beast's Resonance rose under his feet. That skill had no element or attribute, but it was the most essential one for a Beastmaster. Besides controlling beasts, it allowed the Beastmaster to form a mental connection with them. He could issue skill commands without speaking, saving time and letting the beast react instantly. He hadn't used it before because it wasn't needed. Gray could handle those earlier bosses alone. But now, things were different. Gray let out a short howl and waved its claws to show it understood. The little one was usually proud and ignored Aiden, but in battle, it always listened without hesitation. The next second, following Aiden's command, it charged toward the Rogue. '-922' A Monarch-level boss naturally had 20 percent damage reduction. Gray was now Level 8, with a base strength of 850. Its damage hovered around 930. '+1000' A green number appeared above the Rogue's head. It was health regeneration. "As expected." Aiden narrowed his eyes. Bosses at this level always came with advanced attributes like health recovery. This one restored 1,000 Health every second, which was enough to make anyone despair. A Level 10 assassin with the best possible epic equipment—gear that was almost impossible to get at this stage—could only scratch it. The damage wouldn't even keep up with its regeneration. What made things worse was that all Lord-level and above bosses had an advanced attribute called Damage Immunity. If the damage didn't reach a certain threshold, it simply wouldn't count. For example, if the Rogue's threshold was 800, then any attack below 800 would instantly be nullified. That was why Corrupted-level bosses were the limit for guild hunts. Against Lord-level bosses, numbers didn't matter. Even if a million players surrounded it, if no one could break the damage limit, every hit would deal zero damage. Luckily, with Gray's high attack power, that wasn't a problem. "Use Dragon's Breath, then keep attacking." Aiden calmly gave the command. '-4250''-935' '-930' A series of large numbers appeared, and the Rogue's health bar dropped quickly. Even with its crazy regeneration, it couldn't keep up. A pure mage-type boss didn't stand a chance against Gray. It could attack freely without worry. Even without skills, its normal attacks alone reached a terrifying DPS of 1,500. The Rogue's health was dropping fast. 'World-Shaking Dragon's Might.' A sharp light flashed in Aiden's eyes as he gave another quick command. "Roar!" Gray let out a furious roar, and the Rogue was instantly stunned. A blue glow began to gather between its sleeves, but before it could take form, it disappeared. "An instant-cast skill?" Aiden's eyes grew even more alert. The time he took to issue the command was less than half a second, yet the Rogue had almost managed to cast a skill.He wasn't just reacting to the Rogue's movements. He was using experience from his previous life fighting strange creatures and predicting their behavior. The moment the Rogue moved, he sensed the sign of skill activation and reacted immediately. Anyone else, even a top player, wouldn't have been able to do that. They didn't have Aiden's deep understanding of these abnormal creatures. '-930.' '-920.' While the Rogue was stunned, Gray unleashed a flurry of attacks. In just five seconds, it dealt over 10,000 damage. Even with 1,000 Health recovery per second, the boss couldn't catch up. 'Rogue: 43,590 / 50,000' The stun ended. The Rogue raised both hands, and its sleeves began to surge with power.