How to get Extensions
"How do I get those precious extensions" you may ask. Luckily, there are a few ways to get them:
The easiest and cheapest way is to get them through Quests. After defeating all three waves of Enemies, you'll be rewarded with CE and at least one Extension. Quest rewards are either Replica Extensions or Original Extensions.
Another way to get Original Extensions is to compete in the Weekly Cup. Usually, the first ~200 players win an Original Extension. The kind of Extension varies from Cup top Cup and are announced beforehand.
Raids are another form of PvE and is like a massive Raid Boss fight with the whole player base. The more damage you deal during the event, the higher your chances to receive an Original Extension at the end.