Well, 'Re:Monster' is also an interesting one. It's about a guy who gets reincarnated as a goblin in a game - like world. He has to level up his monster self by fighting, gathering resources, and evolving. The story is full of battles and strategic thinking on how to make the most out of his monster abilities.
One common trope is the gradual evolution of the monster's appearance. For example, it might start as a small, unassuming creature and then grow larger and more menacing as it levels up. Another trope is the acquisition of new abilities. As the monster levels up, it could gain powers like flight or the ability to breathe fire. Also, there's often a power struggle within the monster's environment. Other monsters might be jealous or try to stop its growth.
In novel updates, a monster's leveling up can be triggered by multiple factors. It could be by defeating powerful opponents and gaining their strength. It might also evolve as a result of reaching certain milestones or unlocking hidden abilities within itself.
Well, the theme of adaptation is quite common. For example, a character reincarnated as a monster has to adapt to its new form and abilities while leveling up. Also, the exploration of power dynamics is a theme. As the monster levels up, how it relates to other creatures in the power hierarchy changes. There's also the theme of self - discovery. Through the process of leveling up, the character discovers more about themselves and their place in the world.
To level up quickly, focus on completing main story quests. They usually give a lot of experience points. Also, engage in battles with stronger monsters as they offer more exp. Another tip is to use items that boost exp gain during battles.