So master experience is normally allocated to the mastery you choose in the base tree that you’re in (HoT, Central Tyria). When you can no longer accept the mastery experience in that base tree (you ran out of mastery points to use) any new mastery experience you attain goes into a random one – it’s not really random but still.
However, once the first tier mastery is full of experience and you’re out of points, all additional experience you attain goes into the mists, it just disappears, it doesn’t go into the next tier, everything just stops.
