Side Quests
Side quests are typically chosen at The fallback content to display on prerendering quest boards. They are optional opportunities for rewards that are independent of the party's guild quest. Each side quest has its own requirements for completion. The party completes its side quest at the end of an The fallback content to display on prerendering in which that quest's requirements are met (unless the quest specifies a different timing).
Though individual adventurers may choose which side quests to gain, active side quests are shared between the entire party. Your party can have up to 4 active side quests at a time. If the party would gain a side quest and exceed this limit, it must either discard 1 of its current side quests or the side quest it would gain. The party can also choose to discard 1 or more side quests at any time.
There is no inherent penalty for leaving an active side quest uncompleted unless that quest's card says otherwise. If you cannot meet the requirements to complete a side quest, you cannot complete that quest but may keep the card until the end of the session.
Side quests are not specific to a single The fallback content to display on prerendering. Instead, they often refer to map features, such as landmarks, that are found across Tamriel.
Are side quests optional to trigger?
Side quests are only optional if the text says so. If it says "next clash" or similar, you have to do it in the next clash. The only way to opt out is to discard it.
SourceSQ-20 Dice! - this card is allowed to be discarded
This side quest has text that reads: "Keep this quest until the end of the session, as it may be initiated multiple times." This text is intending to tell you that you are allowed to keep it, as normally you would discard a side quest once it's completed. However, you are also allowed to discard this side quest as normal. You are not obligated to hold onto it until the end of the session if you wish to discard it.
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