XP Booster

XP Booster is an XP booster. It can be earned from Battle Chests, at a small chance. XP Boosters give +100% Tower XP and Hero XP. XP Boosters last for a variable amount of time, ranging from 30 minutes, 1 hour, and 2 hours, depending on the rarity of that booster.

XP Boosters can stack with other XP boosts such as watchable ads and/or VIP, but only additively.

Summary
XP Boosters are precious, and make sure that any earned XP Boosters coincide with times of the day where you can afford to play the game for long periods. Avoid opening chests near bedtime or close to time-sensitive IRL events due to the possibility of obtaining a XP booster at an inopportune time. Make full use of XP Boosters when they are active and do not rely on having them as a clutch for XP generation.

If XP Boosters are earned, opt for short games and use this opportunity to unlock XP for towers. Using either the least experienced towers or the most experienced towers is often optimal for making the most of them. Go and do as many games as possible, as this is time-based.

Tips

 * XP Boosters are especially precious for free-to-play players, especially those without VIP.
 * Note that if the XP Booster runs out in the middle of a game, then you will still get the XP bonus for that game.