So, the 50% experience chest reward apparently gives you half the xp on your current level. Essentially, it has better value for later levels. I think I learned it from one of OHRye's videos. Also, people kept saying level 25 was max but I'm pretty sure it's just bugged. To level up past 25, I think you need 3-4 levels worth of xp, then you get all 3-4 upgrades at once. Pretty much a rubber band effect.
