经验加成可以用英语表示为 "experience bonus" 或 "experience boost"。
例句：
这个角色的经验加成使他比其他角色更快地升级。(The character's experience bonus allows him to level up faster than other characters.)
我们正在举办一个活动，为玩家提供经验加成。(We are holding an event that provides players with an experience boost.)