Talk:Bloons Tower Defense 5/@comment-213.112.168.41-20111219001920/@comment-81.159.194.211-20111222190732

Once you've unlocked every tower, when you continue to rank up you get the tier 4 upgrades. The 3 upgrades before can be unlocked by XP and you get more by popping bloons with that tower. You also need the XP to unlock the tier 4 upgrades but you must get to the rank needed to unlock XP towards it. HOPE IT HELPS!