1. Event - get more rewards
2. Main - to open upper contents
3. Side Story - until you get all side only characters
4. Supply - when you did all 1~3 but you have Eterniums left (check more details below)
As this [World Flipper] guide is focused on guiding beginners / returning players on how to progress through the game, not all game mechanics / points will be covered in depth. For further questions like team compositions, please ask them in the #questions of the EN Discord.
This [Counter:Side] Guide is based on the current META on SEA server of the game, which is 1.5 years behind KR version and 6 months behind TW. Since we don't have access to many characters, whose best at what will differ. But please note, it's not worth chasing an unit that's good now, but will become meh later down the line