Changelings are creatures from the second season of MLP: Frendship is Magic. As in the show, they can take the form of other ponies, disguising themselves as the Mane 6 in this case. Once revealed, they are similar to parasprites, being obstacles that need to be cleared by using the appropriate type of Element Shard. Unlike parasprites, one changeling will take up 5 elemental shards to defeat. Each one stands in the center of a little crater which acts as an impediment to building, which will only disappear after the changeling has been defeated.
Note: On some devices the crater will not be properly removed after the changeling's defeat, or the changeling will just stand there without the aura. It should be gone on your next visit to Canterlot, however.
Note: Changelings can sometimes land on the bottom borders of the terrain, which can make it difficult to tap them. Zooming in might help.
Uncovering Changelings Edit
Second, they can show up in disguise as any member of the Mane 6. If you go to Canterlot you may see several copies of Mane 6 ponies running around. Only one of each of them is the real one. Simply tap on each one and if they respond as usual they are real. If they are a changeling they will reveal themselves as such, jump and disappear in a column of coloured light and land somewhere in your clear zones creating its crater.
Even when disguised as a pony you can often tell which copies are changelings with careful observation of their behavior. Disguised changelings will wander anywhere on the map, even well into the shadowed zones. They are also not as social as regular ponies in that they wont chat or play with a group of others and are usually found alone (they'll stop if blocked and other ponies might stop for them so seeing a pony in a crowd isn't a reliable way to weed out changelings). One last method applies specifically to Twilight Sparkle. If you have advanced to the point where Twilight has become a princess she will have wings and a crown -- but disguised changelings will still appear to be regular unicorns.
Clearing Changelings Edit
To clear changelings tap on them 5 times. They have a 'health bar' with 5 lines, representing the 5 shards needed to defeat them. Each time you tap on them, you use a shard to lower their health.
When clearing changelings, you can obtain bits as a reward on the removal of each bar. There is also a small chance that a single gem may pop out when you defeat it.
As a part of the quest series in Canterlot there are several quests that will require you to uncover and/or defeat changelings.
In addition near to the end of the questline, you wil have to defeat Queen Chrysalis by clearing 6 waves of changelings, each consisting of 8 changelings of the same type. Each wave must be cleared completely before the next one spawns.
However, unlike in the series, defeating her will not stop changelings from spawning. Just like parasprites, changelings will continue to spawn in their various forms.
Types of Changelings Edit
There are 6 types of changelings, matching each of the Elements of Harmony. They can be distinguished by the colors surrounding the rim of the crater.